Marcy duetted with Alice Cooper on his 1978 album From the Inside (producer David Foster) on the song “Millie and Billie”. She provided backing vocals on the 1980 hit “Lookin’ for Love” (#5 Pop and #1 Country) by Johnny Lee. Also in 1980, she sang a duet with Robin Gibb, “Help Me!”, which was featured on the official soundtrack of the film Times Square. The song was released as a single, and reached number 50 on the US Billboard Hot 100. She also sang a duet on Jimmy Ruffin’s album Sunrise; “Where Do I Go”, and in 1981 was featured on the official soundtrack of American Pop on “Somebody to Love”. During this period, Detroit was signed to Epic Records and released her debut album, Marcella in 1982. The album failed to appear on any major charts, and after the commercial failure of the album, Epic Records refused Detroit tour allowance with John Mellencamp, and she was later dropped by the label. She wrote and provided backing vocals for “Tangled in Love” with Richard Feldman, which appeared on Eric Clapton’s 1985 album Behind the Sun. Following this, she was asked by Clapton to start to work with him again, and after another year of touring with him, she again left to pursue her own solo career again. Detroit (credited as Marcy Levy) released a LP together with Diane Reeves in 1985, titled Ballerina, where she performs three songs, “Ballerina”, “Pretty Polly” and “Always A Woman In Love”. Also credited as Marcy Levy, she sang a duet with Max Carl, “Come and Follow Me” for the movie Short Circuit 1 in 1986; however no movie soundtrack album was ever released. Detroit was featured in 1988 on the official soundtrack of Mac and Me, on the song “You Knew What You Were Doing”.

Detroit has co-written many songs for other artists, starting when she was part of Eric Clapton’s backing band in the 1970s. She most famously co-wrote “Lay Down Sally” for him, which was a #3 hit in the USA in 1978, and contributed other songs for his albums No Reason to Cry, Slowhand, and Backless.

In late 1991, Shakespears Sister released the first single from their second album Hormonally Yours, “Goodbye Cruel World”, which was also a commercial failure, failing to peak within the UK top 50. The second single however, “Stay”, marked Shakespears Sister’s first and only number one, staying at the top of the UK charts for eight consecutive weeks, and also found similar success in international charts. Hormonally Yours was released the following month, and was certified 2× Platinum by the BPI. The duo continued to enjoy success with further singles from Hormonally Yours; “I Don’t Care” peaked at number seven, “Hello (Turn Your Radio On)” at number 14, and a re-release of “Goodbye Cruel World” at number 32.

Detroit is married to Lance Aston (one time member of Prima Donna and brother of Bucks Fizz star Jay Aston). They have a son, Maxwell, born in 1991.

After leaving Shakespears Sister in 1993, Detroit began her own solo career also with London Records. Her second studio album, and her first since leaving the duo, Jewel was released in March 1994 preceded by “I Believe”, which reached number 11 in the UK. The album itself reached number 15 and was certified silver by the BPI. Jewel received mixed reviews from critics – Aaron Badgley from Allmusic commented “[Chris Thomas] seems to steer Marcella into mid-’90s dance grooves, which does not always fit her own distinctive sound”. Three more singles followed; “Ain’t Nothing Like the Real Thing” (a duet with Elton John), “I’m No Angel”, and “Perfect World”, which peaked at number 24, 33, and 134 respectively.

Detroit left London Records sometime in 1995. She released her third studio album Feeler in September 1996 under various labels; in the UK it was released under AAA Records, in some European territories under Mega Records, in others Silvertone Records. The album did not chart in the UK, or any other territories except Japan, where under Sony Records it peaked at number 82. Four singles were released, “I Hate You Now…”, “Somebody’s Mother”, “Boy”, and “Flower”. “I Hate You Now…” and “Boy” peaked at number 107, and 102 respectively. A live album, Without Medication Plus MTV “Buzz Live”, was released promotionally in Japan in 1996. In the same year, she guest-starred in two episodes of Absolutely Fabulous as an angel. Over the course of the two episodes, five original songs by Detroit feature in numerous scenes, which were later released in 1999 on Abfab Songs. The same year, Detroit released Demoz, a double-CD collection of demos. Her fourth solo album, Dancing Madly Sideways was released in July 2001 under Detroit’s own independent label Banned Records, which would later be retitled Lofi Records. The album was preceded by one single, “Lust for Like”, and a three-track sampler EP, Limited Edition. None of these releases charted internationally. In 2002, she featured on Aurora’s single “If You Could Read My Mind”.

After Dancing Madly Sideways, Detroit formed her own self-titled blues band (named after her birth name and original stage name); the Marcy Levy Band with Michael Fell on harmonica, Job Striles on guitar, Rick Reed on bass and Max Bangwell on drums. Detroit described the project as “getting back to my roots, the stuff that inspired me in the first place. So I decided to contact all my blues friends and do a record.” Their debut EP Button Fly Blues received a limited release under Handmade Records, Detroit and the band’s only release with the label. During this era, she toured with Carlos Guitarlos, and began songwriting for artists including Charlotte Church and Alex Parks, among others. The Marcy Levy Band released their debut studio album The Upside of Being Down in July 2006 under Detroit’s independent label Lofi Records. In April 2007, she featured on Loverush U.K.’s single “Mystery to Me”. In 2008, she also featured on “My Friend Misery” by Vacuum.

In 2009, the Marcy Levy Band split. The same year, Detroit featured on Alex Dixon’s – grandson of Willie Dixon – album Rising from the Bushes on two tracks: “Fantasy” and “Paint You a Picture”. As of mid-2009, Detroit had been working on two separate solo studio albums; Skin I’m In, produced by Larry Klein, and The Vehicle, a more personal project, and is to coincide with the release of her autobiography of the same name. In January 2010 Detroit participated in Series 1 of the British ITV1 celebrity reality television show Popstar to Operastar. She finished as a joint semi-finalist alongside Kym Marsh in week 5 of the competition. When the voting statistics were released it was revealed that she had more votes than Marsh; therefore she came third overall. She was also only three percent behind Darius Campbell, who went on to become the winner of the season. In 2010, she released a single titled “All is Forgiven”, based on the Irish Prayer, which has since been removed from the iTunes Store. In November 2011, Detroit released her first Christmas EP Happy Holiday, consisting of classic covers and an original song of the same name.

In May 2012, Detroit released her first single in two years; “Madison’s Light” as a tribute to her niece, who died at the age of five months. Five months after the release of the single, Detroit officially set up the not-for-profit charity organization “The Madison Morr Foundation” for children in need. Detroit was featured on the song “Yell Cut” among numerous artists including Anthony Costa, originally written by aspiring singer Natasha Anastasi, who was killed in a car accident in 2005. The song was recorded for and included on Anastasi’s tribute album Natasha, released in June 2012 consisting of songs performed by Anastasi and other artists. In August 2012, Detroit announced James Gadson would be featuring on her “new album” (which one hasn’t been specified) and would be performing on her tour with her, which opened on September 20, 2012 in Largo, Florida. In September 2012, she released a new single “Love, Faith, and Hope”, which was intended to be the official anthem of the Belgrade Pride festival, which was cancelled by the Serbian government due to security reasons. In November 2012, Detroit released her second Christmas EP, entitled Holiday 2012, and confirmed on her official Facebook page that both albums (Skin I’m In and The Vehicle) were completed, and awaiting release for early 2013.

It was announced in December 2012 that Detroit is expecting to release both albums internationally on Valentine’s Day, 2013. She is also currently developing an official app, which will be released free, and shall contain exclusive information “you won’t be able to find anywhere else”. A supporting tour backed by London session organisation The AllStars Collective, the Vehicle Jump Start Tour, opened on April 28, 2013 in Milton Keynes, United Kingdom. Detroit announced in February 2013 that she had signed with Right Recordings, a UK-based label with “major distribution through Universal”.

During this period however, tensions began to arise between the two. A concert at The Royal Albert Hall was cancelled due to Fahey’s own personal issues at the time, and the two decided to put Shakespears Sister on hiatus for Detroit to release her new solo album, which she had been working on at the time, and also for Fahey to “take that time off to be with her family.” During this period, the fifth and final single from Hormonally Yours was released; “My 16th Apology”, and due to both members being unable to promote it, it was a commercial failure, reaching number 63 on the UK charts. Detroit found out that Fahey had ended her partnership with her at the 1993 Ivor Novello Awards ceremony through Fahey’s publisher when Hormonally Yours won “Best Contemporary Collection of Songs”. Detroit and Fahey had not spoken to or seen each other for 25 years, before eventually meeting and talking again in 2018.