After graduating from the University of South Florida with an engineering degree, Gallagher got his first taste of life on tour in 1976 as Jim Stafford's road manager. Stafford and Gallagher went out to California in 1979 and Gallagher decided to take the stage himself. He began honing his own comedy act while hanging out at both the Comedy Store and the Ice House. As his audience grew, Gallagher became most noted for wielding his trademark Sledge-O-Matic. He showered his audience with the pulverized remains of apples, oranges, lettuce, cottage cheese, pound cakes, Big Macs and of course, no show can end without the Watermelon finale. Show goers turn up already Gallagherized, wearing plastic raincoats, goggles, sunglasses, umbrellas, and windshield wipers and refer to the front of the theatre as Death Row.

Gallagher has the distinction of being the first real star to come out of cable television. To date he has done sixteen specials: Uncensored Evening, Mad As Hell, Too Real, Totally New, That's Stupid, Stuck in the 60's, The Maddest, Melon Crazy, The Bookkeeper, Over Your Head, The Messiest Of, Overboard, The Leap Year Marathon, We Need A Hero, Smashing Cheeseheads, and the most recent, Sledge-o-matic.com.

Before every show, Gallagher has an autograph signing party in the lobby, where fans can get his autograph and a picture with him. Flash photography is allowed at every Gallagher event. He even sells cameras if you forget yours! A Gallagher concert is an unforgettable experience. He is a keen and original observer of human nature and the American "scene". "My humor makes people think," Gallagher says. "I want people to look more closely at this country and their lives to see the humor and absurdity in it all …I don't have to make it up, the truth is funny enough."

Gallagher was recently featured on televisions E True Hollywood Story. In June of 2000, Gallagher suffered a mild heart attack despite no previous history of heart problems. He rebounded quickly and continues to perform with amazing energy. In August of 2000, a federal judge ruled in Gallagher's favor in a lawsuit against his younger brother, Ron. An injunction was granted prohibiting Ron from performing any act that impersonates his brother in small clubs and venues. Ron had been touring as a Gallagher impersonator with Gallagher's permission but Ron was charged with deliberately misleading the public with false advertising that suggested they were seeing the real Gallagher. In 2000, Gallagher was honored by the University of South Florida as one of its famous alumni and by
Florida Living Magazine as one of the top "100 Legends" of Florida.