In 1970, now signed to Roulette Records, the Three Degrees scored their first national chart hit with a remake of the Chantels' "Maybe". It went to number four R&B in summer 1970. The follow-up, "I Do Take You," peaked at number seven R&B. Barrett got the group short-term deals with Warner Bros., Metromedia, and Gamble & Huff's Neptune Label. The group had a cameo in the classic 1971 movie The French Connection starring Gene Hackman and toured with Engelbert Humperdink. In 1973, Barrett worked a deal with Gamble & Huff's Philadelphia International Records (PIR). The Three Degrees' first PIR single was "Dirty Ol' Man," a disco hit. A short time later, Don Cornelius, producer and host of TV's Soul Train, approached Gamble & Huff about coming up with a new theme song for his hit syndicated show. The Three Degrees were asked to do vocals at the end of the show's new theme track. After some airings, public demand forced the TV show's theme to be released as a single. "TSOP (The Sound of Philadelphia)" by MFSB featuring the Three Degrees went gold hitting number one R&B and holding the number one pop for two weeks during spring 1974. Meanwhile, a previously released Three Degrees single, "Year of Decision," stalled at number 74 R&B. Another MFSB/Three Degrees single, "Love Is the Message," peaked at number 42 R&B in the summer of that year. In the summer of 1974, PIR released another single on the group, "When Will I See You Again." The single went platinum, selling over two million copies, going to number four R&B and number two pop around September 1974. Their PIR debut album, The Three Degrees, was released at the end of 1974. The follow-up, "I Didn't Know," written and produced by Bunny Sigler, went to number 18 R&B in early 1975. The group performed the song on a guest appearance on the hit NBC show Sanford and Son. Their only other charting PIR single was "Take Good Care of Yourself" (number 64 R&B in summer 1975).

Around 1976, Pickney left the group and was replaced by returning member Helen Scott. CBS released their album Standing up for Love in the U.S. in 1977. In 1978, the Three Degrees were signed to European label Ariola Records. The group recorded three LPs for the label. Longtime favorites in the U.K., the group performed at Buckingham Palace for Prince Charles' 30th birthday party and they were guests at his wedding to Princess Diana. During the first half of the '80s, the Three Degrees released U.K.-issued albums, Album of Love and Live in the UK and singles, "Liar" and "A Sonnet to Love." Stock/Aitken/Waterman produced a 1985 U.K. chart hit, "The Heaven I Need," on the group for Supreme Records. In 1986, Sheila Ferguson left the group. With Helen Scott, Valerie Holiday, and Victoria Wallace, the group recorded an album for Ichiban Records, ...And Holding! The act recorded another live CD with Billy Paul and Harold Melvin and the Bluenotes during a TSOP tour in the summer of 1989. Scott, Holiday, and new member Cynthia Garrison recorded three albums in the 1990s.