The group, known originally as Unique Attraction, was founded during 1986 at the Philadelphia High School for Creative and Performing Arts, in Philadelphia, Pennsylvania. There, friends Nathan Morris and Marc Nelson organized several R&B singing groups, all of which ended soon. Eventually, they recruited tenors Wanya Morris and Shawn Stockman and bass Michael McCary.

They found inspiration in New Edition's harmonies and routines, and eventually renamed the group "Boyz II Men", after one of New Edition's songs. In 1989, they snuck backstage after a concert performed by Bell Biv DeVoe, a New Edition spin-off group. Boyz II Men performed an acappella rendition of New Edition's "Can You Stand the Rain" for New Edition/BBD member Michael Bivins. Bivins was impressed by the group, and began plans to contract them to Motown Records through a production deal with his Biv Ten Records company. But before the group began recording, Marc Nelson left because of personality conflicts, reducing the quintet to a quartet. Other early workings include work with Michael Jackson.

A year before releasing their debut album, they made an appearance on a solo album by Visam Ahmed. They are listed in the credits as singing background vocals on the song "One Mile from Paradise" as "Boy's to Men".

Boyz II Men's first album, Cooleyhighharmony, was released on Motown in 1991 and was executive produced by Michael Bivins. Cooleyhighharmony's drum-heavy new jack swing sound and multi-layered sampled backdrops were similar to that of Bell Biv DeVoe's own work, but featured classic-soul styled vocals in place of BBD's rapping and brassier singing. This style was dubbed "hip hop doo wop" by the group and Bivins, who presented Boyz II Men and adolescent R&B group Another Bad Creation to the public as BBD's protégés.

Boyz II Men's first single, the Dallas Austin-produced "Motownphilly" featured a rap cameo by Michael Bivins, and was accompanied with a music video that presented the group in hip hop style. (The video also included cameos from fellow CAPA alumni Black Thought and Questlove of The Roots) Their second single was a cover of a classic Motown tune, G.C. Cameron's "It's So Hard to Say Goodbye to Yesterday" from the 1975 film Cooley High, while "Uhh Ahh" served as the third single.

From the beginning, Boyz II Men featured all four members as leads, avoiding the usual R&B group arrangement of one or two lead singers and a team of background singers. The multiple-lead arrangement became a Boyz II Men trademark, and it became typical to hear Wanya Morris' vibrato-heavy tenor, Shawn Stockman's tenor voice, Nathan Morris' baritone, and Michael McCary's bass (often used in spoken-word sections of many Boyz II Men hits) trading bars in each song.

The album's liner notes identified nicknames for each member of the group. These nicknames were devised in collaboration with Bivins in an attempt at marketing. Wanya was "Squirt", Shawn was "Slim", Michael was simply "Bass", and Nathan assumed the name "Alex Vanderpool", after a soap opera character who brandished a nerdy style.

In time, Nathan Morris would become something of the de facto manager of the group, handling its operations and business interests, but the group never presented one man as more important than the other.

Cooleyhighharmony was a major success, eventually selling over nine million copies and winning the Grammy Award for Best R&B Performance by a Duo or Group with Vocals at the 1992 Grammy Awards, they were also nominated for Best New Artist, alongside with British singer-songwriter Seal, Color Me Badd, as well as C+C Music Factory, but lost to singer-songwriter Marc Cohn. . "Motownphilly" and "It's So Hard to Say Goodbye to Yesterday" were number 1 R&B hits and top five U.S. pop hits, and Boyz II Men joined MC Hammer's high-profile 2 Legit 2 Quit tour as an opening act. While traveling the country, their tour manager Khalil Roundtree was murdered, and the group's future performances of "It's So Hard to Say Goodbye to Yesterday" were dedicated to him.

While touring during 1992, Boyz II Men returned briefly to the studio to record the single "End of the Road", co-written and produced by Kenneth "Babyface" Edmonds, for the soundtrack to Eddie Murphy's film Boomerang. "End of the Road" became a record-breaking success, remaining at number 1 on the Billboard Hot 100 for thirteen weeks, breaking the previous record of 11 weeks set by Elvis Presley with "Don't Be Cruel"/"Hound Dog" in 1956. Cooleyhighharmony was reissued during 1993, with "End of the Road" added as a special bonus track. It has been said that the song was recorded in four hours.

During 1994 Boyz II Men's second album, II, was released. Most of the tracks on II were written and produced by Tim & Bob Tim Kelley and Bob Robinson (5) Babyface (2) and the successful team of Jimmy Jam & Terry Lewis (2); Michael Bivins distanced himself from Boyz II Men to focus on developing new acts. Several of II's tracks became major singles, among them Jam & Lewis's "On Bended Knee", and Babyface's "I'll Make Love to You" and "Water Runs Dry". "Thank You" and the hip hop soul track "Vibin'" both missed the U.S. Top 20; but "Water Runs Dry" became number 2, and "I'll Make Love to You and "On Bended Knee" became number 1 hits.

"I'll Make Love to You" broke "End of the Road's" 13-week record at number 1, by spending 14 weeks at the top of the chart (a feat equaled earlier that year by Whitney Houston's cover of "I Will Always Love You"). "On Bended Knee" replaced "I'll Make Love to you" at number 1, making Boyz II Men the third act to replace themselves at number 1, after Elvis and The Beatles. Meanwhile, II sold more than 12 million copies in the United States alone, becoming one of the best-selling albums ever released by an R&B group act.

At the 37th Grammy Awards on March 1, 1995, the group won two Grammy Awards: Best R&B Album for II and Best R&B Performance by a Duo or Group with Vocals. for "I'll Make Love To You".

By this time, Boyz II Men were a popular act, not only in the U.S, but worldwide. Boyz II Men became recognized as something of a 1990s version of The Temptations, the 1960s Motown act that became the label's best-selling male group act. Many of the elements that made The Temptations, other classic Motown artists such as The Four Tops and Smokey Robinson & the Miracles, and Boyz II Men's mentors New Edition successful were adapted by the group, including a clean-cut image, smooth harmonies, and synchronized dance and performance movements. The members of Boyz II Men were particularly noted for their vocal abilities, and helped continue a trend in R&B towards an emphasis on emotive singing with significant use of melisma, a trademark of Wanya Morris' singing. Boy II Men also credit legendary gospel supergroup Commissioned (gospel group) as a heavy influence of their silky smooth harmonies.

Several R&B competitors began showing obvious inspiration from Boyz II Men's work and singing style, among them, Shai, Soul for Real, BLACKstreet, All-4-One, and later Dru Hill, Jagged Edge, and (featuring old Boyz II Men member Marc Nelson) Az Yet. Boyz II Men's closest competitor, Uptown Records act Jodeci, were, with their more sexually charged style, quite different from Boyz II Men's wholesomeness. Jodeci's style had its own followers (many of them, Dru Hill and Jagged Edge in particular, they shared with Boyz II Men), but their influence on the music industry as a whole was not as widespread as that of Boyz II Men.

Also notable is that several record producers, Lou Pearlman in particular, developed several acts in the same style as Boyz II Men, but with male Caucasian singers instead of African-American ones. Because of this, Boyz II Men is often considered to have continued the "boy band" craze started by New Edition in the US (a genre already popular in the UK and Europe with bands such as Take That, Boyzone and East 17 selling millions across the globe) that reached a climax by the end of the 1990s, with groups such as The Backstreet Boys and *NSYNC, going on to widespread international success, and others, such as Motown act 98 Degrees, finding more moderate mainstream success.

The Motown company issued The Remix Collection, a compilation of remixes of various Boyz II Men songs from Cooleyhighharmony and II. The group itself had opposed the release of the collection, and as a result there was a dispute between the company and the group. Boyz II Men initiated their own recording company Stonecreek (which released material by artists such as Uncle Sam) to be distributed by Epic Records, not Motown.

Evolution was released during 1997 to mixed reviews and sold three million copies, far below II's 12 million and Cooleyhighharmony's 9 million. Only one of Evolution's singles, the Jam/Lewis-penned "Four Seasons of Loneliness", charted at number 1. The second single, the Babyface-helmed "A Song for Mama" (the theme song to the Babyface-produced film Soul Food) was a Top 10 success, but the follow-up "Can't Let Her Go" underperformed.

As the label problems mounted, health problems began to take their toll on the group. While on tour to support the Evolution album, Wanya Morris developed a polyp on his vocal cords, and the group was forced to postpone part of the tour until he recovered. When the group appeared on Keenen Ivory Wayans' short-lived talk show just before the album's release, McCary danced along with the other members as they performed "Motownphilly".

Boyz II Men's final Top 40 hit was "I Will Get There", a Diane Warren-penned single released in support of the soundtrack to DreamWorks' first animated feature, The Prince of Egypt.

They were nominated for 2 Grammys in 1998: Best R&B Album for Evolution and Best R&B Vocal Performance by a Duo or Group for "A Song For Mama".

In 1999, Motown's parent company, Polygram, was bought by Universal Music Group. Amidst the major corporate restructure, Motown was merged with UMG's Universal Records, where Boyz II Men found themselves reassigned. It was during this time the group performed "America the Beautiful" at Wrestlemania XV.

Their only studio LP album for Universal, 2000's Nathan Michael Shawn Wanya, was chiefly written and produced by the group itself, in an attempt to update their sound and ward off critics who questioned the group's reliance on Babyface's hit-making songcraft. While the critics were more receptive to Nathan Michael Shawn Wanya than they had been to its predecessor, the LP sold 500,000 copies in the US, 1 million copies worldwide, and although its two singles, "Pass You By" and "Thank You in Advance" received media attention, neither became hits.

Meanwhile, Michael McCary was diagnosed with scoliosis, which limited his ability to dance at live performances. The other three members eventually resorted to having McCary seated on a stool while they did the dancing themselves.

Boyz II Men departed from Universal in 2001, and the label released a greatest hits collection, Legacy: The Greatest Hits Collection, to close out their contract. Signing a new deal with Arista Records in 2002, Boyz II Men began recording the Full Circle album, and recruited Babyface for a new single, "The Color of Love". Arista commissioned a high-budget music video, shot in four different locales by four different directors: supervising director Little X filmed scenes featuring Michael McCary in India, Hype Williams filmed Shawn Stockman in Tokyo, Benny Boom filmed Nathan Morris in Ghana, and Chris Robinson filmed Wanya Morris in Puerto Rico and finally all were filmed in New York. The resulting music video had a debut on BET, but failed to have a great effect, and Full Circle, like Nathan Michael Shawn Wanya before it, sold slightly more than 500,000 copies in the US and 1 million copies worldwide.

On January 30, 2003, Michael McCary retired from performing due to his ongoing battle with scoliosis. Arista terminated Boyz II Men's contract on April 30, and the remaining three members took a temporary hiatus from the music industry. After a year out of the spotlight, Boyz II Men created the independent label MSM Music Group (distributed through Koch Records), and released the Throwback, Vol. 1 LP, a collection of covers of songs such as The Dazz Band's "Let It Whip", Michael Jackson's "Human Nature", and, as the single, Bobby Caldwell's "What You Won't Do for Love". For the record, Nathan took on the bass lines as well as the baritone vocals that he sang when Boyz II men was a quartet. Throwback, Vol. 1 reached number 59 on the Billboard 200. The group launched an independent tour of North America and Asia in support of the Throwback series. The album has sold over 200,000 copies to date with little to no promotion. Boyz II Men's seventh studio album, The Remedy, was released in Japan at the autumn of 2006. In other regions, it was made available exclusively online through their website BoyzIIMen.com on February 14, 2007.

In mid-2007, the group resigned with Universal Records and released the LP Motown: A Journey Through Hitsville USA through Decca Records. The LP is a cover album featuring songs from the Motown Records catalog, co-produced by Randy Jackson of American Idol fame. The Motown album includes covers of songs by The Temptations ("Just My Imagination (Running Away with Me)"), Marvin Gaye ("Ain't Nothing Like the Real Thing", "Mercy Mercy Me"), Smokey Robinson & the Miracles ("The Tracks of My Tears"), and even Boyz II Men themselves (an a cappella version of "End of the Road"). Executive Producers for the album were David Simone and Winston Simone. On October 25, 2007, the trio performed "God Bless America" during the seventh inning stretch of Game 2 of the 2007 World Series between the Boston Red Sox and the Colorado Rockies at Fenway Park.. On November 3, 2007, the group performed as special guests on the hit ITV talent show, The X Factor. On November 10, the band appeared in the Japanese television show, Music Fair21 singing, "Just My Imagination", "It's the Same Old Song", "Reach Out (I'll Be There)" and "I'll Make Love to You" featuring artist AI and her newest song "ONE". On November 13, 2007, Boyz II Men had a CD signing and a performance at the FYE store in Philadelphia despite having been asked by their label to be in either New York or L.A. for the release of the album. Contrary to reports Boyz II Men promoted the release of their new album at FYE in New York. They performed an a cappella version of their smash hit "End Of The Road", and "Just My Imagination" from the new album.

The "Kurt Browning's Gotta Skate" special aired on NBC on November 11, 2007. The special featured Olympic skaters skating to the hits of Motown performed by Boyz II Men and The Temptations. Each group promoted their new albums; Boyz II Men promoting Motown: A Journey Through Hitsville US and The Temptations promoting Back To Front, an album of famous 1970's covers which released on October 23, 2007.

On a February 21, 2008 episode of the Fox music-themed game show Don't Forget the Lyrics!, the group appeared as contestants on the show, playing for charity. After blazing through categories such as Motown, R&B, and even one named Boyz II Men, the group won $500,000 and split the sum between two charities. As a promotion for the Hitsville CD, everyone in the audience got a free copy of the album.

Boyz II Men recorded "Ain't Nothing Like The Real Thing" with German singer Joana Zimmer for her third album Showtime, which was released on May 30, 2008.

For the 51st Annual Grammy Awards, Boyz II Men received two nominations for the album Motown: A Journey Through Hitsville USA (Best R&B Album and Best R&B Performance By A Duo Or Group With Vocals for "Ribbon In The Sky").

In 2009, Boyz II Men announced plans for a new cover album, that covers "artists I don’t think people would expect us to cover!" according to Shawn Stockman. Entitled "Love", the album was released on November 24, 2009. On September 6, 2009 at a concert in Virginia Beach, VA, Shawn announced a 20th Anniversary album in 2011 that would "include all 4 members," sparking a tremendous applause at the news of Michael McCary's return to the group after 6 year absence.

On 10th January 2010, an announcment was made on the official Boyz II Men website, that Michael McCary would not be re-joining the band due to him requesting too much money.