Growing up in the Roseland area of Chicago, DeYoung started his career as an accordionist in 1962 at the age of 15 when he teamed up with his 13-year-old neighbors Chuck and John Panozzo in a three-piece combo originally called The Tradewinds.

During this period, the band played a number of small venues and school auditoriums in an effort to secure a record deal.

From the start of Styx's commercial success with the 1973 DeYoung-penned single "Lady", DeYoung became the creative force behind most of the band's hit songs.

DeYoung wrote and sang lead on seven of the band's eight top 10 Billboard Hot 100-ranked hits during this period, with Tommy Shaw's "Too Much Time on My Hands" (No.

DeYoung's songs often had a grandiose style to them in the tradition of 1970s theatrical rock, which heavily influenced the group's direction in the late 1970s, culminating in the concept albums Paradise Theatre (1981) and Kilroy Was Here (1983).

DeYoung's solo career continued with Back to the World (1986),[1] which contained the singles "Call Me" and "This Is the Time", which was featured in the soundtrack of Karate Kid II (1986) movie.

In 1990, Styx (minus Tommy Shaw, who was replaced by guitarist/singer-songwriter Glen Burtnik) returned to the studio for the album Edge of the Century (1990).

"Show Me the Way", a track written by DeYoung for his son Matthew, received extensive radio play, peaking at #3 on the Billboard Hot 100 singles chart (Styx's 8th top 10 single, and 7th written and sung by DeYoung) particularly after a number of radio stations mixed it with voice tracks of members of Congress debating whether or not to send troops to the first Persian Gulf War.

While touring with Jesus Christ Superstar, DeYoung began writing the book and score of a musical of his own based on Victor Hugo's 1831 novel The Hunchback of Notre-Dame.

James Young and Tommy Shaw of Styx suggested booking a tour in support of the Brave New World album.

Bassist Chuck Panozzo, no longer actively touring with Styx due to health problems associated with his HIV-positive status, offered a more hopeful tone to a writer doing a story on the band for tampabay.com; while reflecting on the effect the loss of his fraternal twin brother, John had on the band, Panozzo noted, "Before any more of us die, I would hope that it could happen.

"[6] In February 2000, DeYoung was approached to perform a concert featuring his many songs from Styx, as well as his solo works and his 1997 stage musical The Hunchback of Notre Dame, with an orchestra.

His wife Suzanne and sister-in-law Dawn Marie Feusi sang backup, his daughter Carrie Ann was in charge of publicity, while his son Matthew designed the stage lighting.

Healthy once again, DeYoung returned to touring with a 50-piece orchestra augmented by a five-piece rock band, which included Tommy Dziallo on guitar, Hank Horton on bass, and Kyle Woodring (formerly with John Mellencamp and Deana Carter) on drums, all of whom also played shows with DeYoung with or without the orchestra.

DeYoung made his major motion picture debut in 2005's The Perfect Man, in which he played the lead vocalist in a Styx tribute band.

[8] On April 20, 2006, at the Community Theatre in Morristown, New Jersey, DeYoung took to the stage once again with former Styx guitarist and bassist Glen Burtnik as part of his Lost Treasures concert series.

While on stage, the duo opened with the Beatles classic "We Can Work It Out", and also performed "Watching the World Go By" and "All for Love", songs that were originally written for the unreleased Edge of the Century 2 Styx album.

On September 14 and 15, 2006, DeYoung appeared with Hal Sparks on Celebrity Duets, an American reality television show produced by Simon Cowell.

On June 19, 2007, DeYoung released in Canada his fifth solo album, One Hundred Years from Now, marking a return to his rock roots.

On New Year's Eve 2007, he performed "Mr. Roboto", "Come Sail Away" and many other Styx classics to a large audience at Victoria Park in Niagara Falls, Canada, and viewers via live television on CHCH-TV Channel 11.

[11] On September 20, 2008, DeYoung performed at the Rock and Roll Hall of Fame benefit concert for the John Entwistle foundation.

The benefit concert was held at the Koka Booth Amphitheatre in Cary, North Carolina, and featured many other rock and roll musicians.

[12] Following the award ceremony in the Frank Gehry-designed Jay Pritzker Pavilion in Millennium Park in Chicago, DeYoung and his band performed many of Styx's hits in a free concert.

In 2010, DeYoung formed a new band dedicated to the music of Styx, adding guitarist and lead vocalist August Zadra and bassist-vocalist Craig Carter to join John Blasucci, guitarist Jimmy Leahey, Tom Sharpe (who left at the end of 2014 to continue his tenure with Mannheim Steamroller, and was replaced by Mike Morales), and wife Suzanne DeYoung in performing Styx hits "Renegade", "Blue Collar Man" and others as well as DeYoung's solo works.

[13] On October 21, 2014, a 2CD + DVD and Blu-ray package, Dennis DeYoung... And the Music of Styx Live in Los Angeles, was released in the U.S. via Frontiers Records.

The album features fellow Chicago natives guitarist Tom Morello of Rage Against the Machine and Audioslave on a track co-written with Jim Peterik of The Ides of March, formerly of Survivor and 38 Special fame.