Bonaduce made a small appearance in the season five Bewitched episode "Going Ape" (1969), as a young boy in the park whose chimpanzee follows Samantha (Elizabeth Montgomery) and Tabitha (Erin Murphy) home.

In the television series The Partridge Family, Bonaduce played the role of Danny Partridge, a member of the musical Partridge family. In the show, the Partridges were a family band that toured the country in their hip, Mondrian-inspired, painted school bus. Danny Partridge played bass guitar for the band and his younger siblings, Tracy and Chris, contributed to the band as percussionists. The series ran for four seasons, from 1970 to 1974 and, in 2003, Bonaduce was honored by the Young Artist Foundation with its Former Child Star "Lifetime Achievement" Award for his role on the series.

Bonaduce's self-titled debut LP was released in 1973 by Lion Records, a subsidiary label of MGM Records.

Bonaduce made several movies during and after the run of The Partridge Family. Perhaps the most memorable of his films was Corvette Summer (1978) starring Mark Hamill. Hamill and Bonaduce played high school students who went in search of a stolen customized Corvette Stingray. Bonaduce also made guest appearances on several TV shows, including the television action drama CHiPs. His career withered in the early 1980s. In his autobiography, Bonaduce said that during a fourteen-year period from 1974 to 1988, he only worked twenty weeks.

In the late 1980s, Bonaduce had become an on-air radio personality. He worked an overnight shift at Philadelphia's WEGX-FM.

In 1985, Bonaduce married Japanese real estate agent Setsuko Hattori. The marriage lasted three years.

On March 9, 1990, he was arrested while attempting to buy cocaine in Daytona Beach, Florida. Ironically, Bonaduce was there to host an event for D.A.R.E., an anti-drug campaign aimed at children. Bonaduce was eventually fired from WEGX. He later became the morning shift DJ at KKFR-FM in Phoenix, Arizona.

On March 31, 1991, Bonaduce was arrested in Phoenix for beating and robbing Darius Barney, a transvestite prostitute; "authorities said the victim suffered a broken nose and a cut to his face." Soon after, he was fired from KKFR. In July of the same year, Bonaduce pleaded guilty to reduced charges. Amongst his punishments, he was required to pay Barney's medical bills. Later that same year, Bonaduce would return to WEGX in Philadelphia.

In April 1994, it was announced that Bonaduce would be making his professional wrestling debut in a "dark match" at the Spring Stampede in Chicago. On April 17, 1994, Bonaduce stepped into the ring at the Rosemont Horizon. His opponent was another 1970s TV star, the Brady Bunch's Christopher Knight. Bonaduce won. Bonaduce had his second professional wrestling match at Total Nonstop Action Wrestling's April pay-per-view event Lockdown against Eric Young, which he lost. Bonaduce was a key player in the series Hulk Hogan's Celebrity Championship Wrestling.

During the 1995-96 TV season, Bonaduce was the host of Danny!, a syndicated talk show featuring the house band The Critics. Some have described this period as being the height of his professional career.

From 2001 to 2003, Bonaduce co-hosted The Other Half, a daytime talk show positioned as a complementary show to The View, on which he starred with Mario Lopez, Dick Clark, and cosmetic surgeon Dr. Jan Adams (who was later replaced by actor Dorian Gregory). During this time, he was also a Hollywood correspondent for the Australian morning show Today.

In 2002, Bonaduce released an autobiography, Random Acts of Badness ISBN 0786867221.

In 2005, Bonaduce starred in Breaking Bonaduce a VH1 reality show about his turbulent life with his wife Gretchen.

In 2006, he had a recurring role in the crime scene drama CSI as a character known as Izzy Delancy – a once great, but philandering, rock star, the victim of the infamous miniature killer. He also hosted the short-lived tabloid-themed game show Starface, on Game Show Network.

As an adult, Bonaduce boxed Donny Osmond in a charity event and later boxed former Brady, Barry Williams, in a separate event. Both contests were won by Bonaduce, gaining a decision over Osmond and a TKO over Williams. On June 11, 2007, it was announced that Bonaduce would box attorney Robert Shapiro for a charitable event.

On September 13, 2008, "Reverend" Bob Levy was defeated by Bonaduce by a TKO in the second one-minute round of a planned three-round fight. Prior to the event, Levy had slapped Bonaduce while visiting Bonaduce's dressing room.

It was announced in early January 2009 that Bonaduce would box against retired baseball player José Canseco at a charity event in the Philadelphia area. Bonaduce reportedly trained for the fight in Sacramento, California with boxing great Angelo Nuñez. On January 24, 2009, Bonaduce and Canseco fought to a majority draw.

Bonaduce began dating his current wife, Amy Railsback, in April 2007. They met at a Starbucks in the Los Angeles area. Railsback, who is 23 years his junior, is a former substitute school Teacher. She now manages Bonaduce's career full-time, runs Gravel Tones Productions Inc, and is occasionally seen in sketches on The Smoking Gun Presents: World's Dumbest... on truTV. Danny proposed to Amy in March 2009, and the couple married on November 22, 2010, at the Four Seasons on Maui, Hawaii. They maintain homes in both Los Angeles and Seattle.

Danny Bonaduce is an ordained minister; he was ordained online in order to perform a wedding ceremony as part of a 94WYSP radio promotion in early 2011.

In 2010, while appearing on a reunion of famous TV families on NBC's Today, David Cassidy remarked, "Whenever Bonaduce gets arrested, for some reason, people call me." The two remained friends and performed together on many occasions in the years following the Partridge Family until Cassidy's death on November 21, 2017.

The younger Bonaduce became famous as a child actor of the 1970s on the TV sitcom The Partridge Family. He co-starred as Danny Partridge, the wisecracking, redheaded middle son of the singing pop band (headed by Shirley Jones). He and Shirley Jones were the only Partridge cast members whose actual first names were also that of the character each portrayed on screen. Danny was the fictional pop group's bass guitar player. Co-starring on the show was Jones's former stepson, David Cassidy; Cassidy and Bonaduce remained close friends until Cassidy's death. On January 20, 2018, Bonaduce attended David Cassidy's memorial Service in Los Angeles.

At age 11, Bonaduce met Academy Award-winning actress/singer, Shirley Jones, on the set of The Partridge Family, where she took him under her wing, and would later became a friend. They worked together, on-camera, for 4 seasons. Off-camera, when he had a horrible homelife, it was Shirley Jones, who was the only one who rescued her child star's crisis, by taking him to her house, everyday. According to his TV mother, who also wrote in her autobiography: A Memoir, that Bonaduce was "smart" and "talented," who was also a troublemaker, off-camera. She also said: "But he was still a kid and would do kid things like get a dish of food and throw it across the room or have a pillow fight," She added: "Danny was a wild child who came from an unhappy home. At eleven, he started smoking." Despite her and the rest of the younger cast: "loved and appreciated him, we couldn’t deny that he was snotty at times. Once, when he was getting too big for his boots, we all ganged up on him and convinced Susan to pour a pitcher of milk over his head, just to put him in his place." The incident was discovered on an episode of The Partridge Family, with David Cassidy, on the other end of the prank. Bonaduce said in a 2012 interview with the Seattle Times if he'd gotten along with his TV mother on The Partridge Family: "Shirley Jones could not have been kinder to me. Although one time she did go a little bit crazy. I think everybody kind of forgot I was 10 years old and expected me to act like a grown-up all the time. One day I was being particularly childish and it obviously made her mad. And she yelled, 'Danny!,' and then pointed upstairs and said, 'Go to your room right now.' I had to explain to her: 'This is a set. There is no upstairs. We don’t really live here. You need to calm down.' She had a good laugh, but I think she’s still embarrassed." When The Partridge Family was over, Danny continues to stay in touch with Shirley, and the two (along with his best buddy David Cassidy), had appeared on many shows, including: A&E Biography, TV Land Confidential and The Today Show, and he was one of the presenters of his TV mother's Intimate Portrait on Lifetime Television. Jones also appeared with Bonaduce (without Cassidy) on his short-lived talk show Danny, for the 25th Anniversary of The Partridge Family., in addition to the 30th and 35th anniversaries. The decade after, Jones watched a couple episodes of Bonaduce's short-lived series, Breaking Bonaduce.