Mary began singing in local clubs and talent contests at age 10. As a teenager, she wrote a song called "Bye Bye Baby" intended for Jackie Wilson. At age 17 she took her composition to the fledgling Motown Records where producer Berry Gordy Jr. Motown was holding open auditions. Gordy not only bought the song, he also signed Mary to a recording contract. Her full-throated approach of that single was quickly toned down in favor of a Pop-Soul sound and the tune soon became Mary's first hit, as it reached the top fifty in 1961. Teamed with producer and songwriter, Smokey Robinson, Wells began a streak of hit singles in 1962 with "The One Who Really Loves You" (#8), followed by "You Beat Me to the Punch" (#9) and "Two Lovers" (#7). Tours of the U.S. and Europe turned her into one of the most popular singers on the Motown label.
In 1964, Mary's career reached a significant peak when her song, "My Guy", made it to #1 on the Billboard Hot 100 chart. She was the first artist to have a top ten song on the Motown label, and also the first to have a #1 song for Motown. She also sang duets with Marvin Gaye, such as "Once Upon a Time", which made it to # 17. The Beatles declared Mary Wells their favorite American singer, calling her "their sweetheart" and invited her to England to tour with them. Upon her return to the States, The Beatles sent Wells several compositions to be released on their next album. In return, Mary recorded an album called "Love Songs to The Beatles".
Mary was just 21 years old when "My Guy" was rising to the top of the charts and was enticed to leave Motown almost immediately afterwards for a reported advance of several hundred thousand dollars from 20th Century Fox. Wells was being groomed for the sort of plans that were subsequently lavished upon Diana Ross, but those dreams were never realised. Mary released five songs on the 20th Century label in 1965 and 1966, but only one, "Use Your Head", made the Top 40 when it landed at #35. It was rumored that Motown quietly discouraged radio stations from playing Wells' subsequent releases. Motown Records had learned a hard lesson and took care throughout the rest of the '60s not to lose its big stars to larger labels. Wells' departure was so dramatic and unsuccessful that it tended to overshadow the quality of her later work, which has almost always been dismissed as trivial by critics. True, it didn't match the quality of her Motown recordings, but her '60s singles for 20th Century Fox, (whom she ended up leaving after only a year) were solid Pop-Soul on which her vocal talents remained undiminished. She drifted to other labels later in the '60s, recording for Atlantic/Atco and Jubilee, and later Reprise and Epic. She wrote and produced much of her late '60s and early '70s sessions and these found her exploring a somewhat earthier groove than her more widely known pop efforts.
Mary divorced her first husband and later married Cecil Womack, brother of '70s recording star Bobby Womack. They had three children, but that marriage also ended in divorce. Throughout the '70s and '80s, Mary toured the country on the oldies circuit. She had a fanatical following and was very well liked by people in the music business. In 1990, Wells was diagnosed with larynx cancer which left unable to sing. A two pack a day smoker, she was financially devastated by her illness as she had no health insurance. Many of her friends, including Mary Wilson and Martha Reeves rallied around her and several artists, including Rod Stewart, Bruce Springsteen and Diana Ross provided financial assistance. Despite her health condition, Mary was always upbeat and courageous.
She began taking long trips, including one to New York where she was the focus of a Joan Rivers show. Her tribute on the program included a warm and generous phone call from Little Richard and a loving video dedication from Stevie Wonder, who, in her honor, sang "My Guy" rewritten as "My Girl". In early Fall 1991, Mary traveled to Washington D.C. where she testified before a Congressional Committee concerning the funding for cancer research. She said: "I'm here today to urge you to keep the faith. I can't cheer you on with all my voice, but I can encourage, and I pray to motivate you with all my heart and soul and whispers." One of Wells' last tours found her sharing the bill with two former members of The Temptations, David Ruffin and Eddie Kendricks, who would both die within 14 months and 3 months of her respectively. After a bout of pneumonia, Wells was admitted to the Kenneth Norris Jr. Cancer Hospital. On July 28th, 1992, the First Lady of Motown died and was laid to rest at Forest Lawn cemetery in Glendale, California. She was just 48 years old.
In 2006, Mary Wells was inducted into the Michigan Rock & Roll Legends Hall of Fame. Her biggest hit, "My Guy", was voted a Legendary Michigan Song in 2009.