Raised in Akron, Ohio, Hewett moved to Los Angeles in 1976, where he met John and Alonzo Daniels, owners of an historical club in the LA Crenshaw district, called Maverick's Flat. It was at Maverick's that Hewett first met Jeffrey Daniel and Jody Watley (eventually Shalamar). Hewett and the Daniels brothers formed a show group called "Beverly Hills" and through Daniels bookings toured throughout Europe, the UK, Scandinavia and Asia for all of 1977 till the middle of 1978. After returning from overseas, Hewett started recording for Jeffrey Bowen, a Motown producer (The Temptations, Commodores, Bonnie Pointer) who was working on a solo project on guitarist Eddie Hazel (Parliament-Funkadelic). Hewett never completed the project because towards the end of 1978, he got a call from Jeffrey Daniel, who was on the road with Shalamar in the middle of a promotional tour. They had suddenly found themselves in need of a lead singer and Daniel made Hewett an offer that he accepted. Within three days Hewett flew to New Jersey, where he met up with Watley and Daniel, rehearsed the lip synch and choreography to the current Shalamar single "Take That To The Bank", and found himself in front of a TV camera on a local dance show in Paterson, New Jersey. They completed the promotional tour and returned to Los Angeles and immediately started recording the Big Fun LP with their producer, Leon Sylvers. The trio went on to record songs such as "Second Time Around", "Make That Move", "A Night to Remember", "Dancing in the Sheets" and the ballad "This Is for the Lover in You". Hewett was the group's lead singer from 1979 until 1985.
When Shalamar broke up in the mid-1980s, Hewett went on to a successful solo career. However, in 1985 before signing his solo deal with Elektra Records, he was arrested and indicted in Miami with his fiancée Mori Molina for possession with an intent to distribute cocaine. Molina, who was indicted in Tampa as well as Miami, was convicted and served prison time; but after a four-day trial, in which Molina testified that Hewett had nothing to do with the crime, Hewett was acquitted of all charges. In spite of his legal battles, Hewett signed his solo deal with Elektra Records and in 1986, before the Miami trial, released his first solo album, I Commit to Love (R&B number 12), a solid urban album that yielded two R&B hits, "I’m for Real" (R&B number 2) and "Stay" (R&B number 8). The album also included "Say Amen", a gospel tune that became a surprise hit on the Gospel as well as Urban charts and is one of Hewett's many signature songs. I Commit to Love was certified Platinum.
In 1990, Hewett released his Platinum self-titled album, which included the hit "Show Me" (R&B number 2), and 1992 saw the release of the LP Allegiance, which was not received as well as previous albums. He contributed to the second season theme song of Hangin' With Mr. Cooper, which was a remake of Sam & Dave's R&B Top 10 hit "Soul Man". This recording was produced by singer Steve Tyrell. After 1995’s It's Time (released by Caliber Records in the US and Expansion Records in the UK), Hewett spent much of his time providing guest vocals on albums by jazz artists such as Joe Sample, Brian Culbertson, and George Duke, among others. In 2000, The Rippingtons featured Hewett on "I Found Heaven" on their Life in the Tropics album. In 2001, Hewett recorded his first full gospel album, The Journey, followed a year later by The Journey Live: From the Heart.
In October 2006, Hewett released a new single, "Enough" (with jazz legend George Duke), which received substantial play on urban contemporary and R&B radio stations. Hewett is signed to The Groove Records, an independent label based in Los Angeles. In October 2008, Hewett released his long-awaited Christmas CD, Howard Hewett Christmas, which combines his soulful R&B voice with classic Christmas songs. Working with music greats Earth, Wind and Fire, Stevie Wonder, and new vocal sensation Jasselle, who provides a Latin flair, Hewett proves that his music style remains classic, offering a message that reignites the spirit of Christmas. In 2009 he recorded a duet with soul singer Teena Marie, "Lover's Lane", on her album Congo Square. Hewett now enjoys recording at his leisure, touring the US and overseas, and spending time with his four children and two grandchildren.