Hammer was a bat boy for the Oakland Athletics professional baseball team from 1972-1980, under team owner Charles Finley. He was the 'eyes and ears' of the bullpen, reporting all goings on to Charles. Hammer would entertain the baseball fans by dancing during the breaks in the games. He received his nickname from baseball great Reggie Jackson, for his resemblance to "Hammerin" Hank Aaron.
Hammer put out his debut album in 1987 titled Feel My Power. It sold over 60,000 copies and caught the attention of the producers at Capitol Records, as well as a few other major recording labels. Hammer signed on with Capitol Records after quite a bit of haggling and a hefty signing bonus. His debut album was then re-released (1988) and renamed as Let's Get It Started, it went on to become triple platinum.
Hammer's popularity started to suffer over the repetitive nature of his lyrics, especially in the single 'Pray', as well as his clean-cut image, and the sampling from various artists on his entire hit singles. Rap artists were not used to his commercial brand of 'pop-rap' as they labeled it, and Ice Cube, Third Bass, and the D.O.C mocked him in their music videos.
Hammer switched to Giant Records to try a heavier sound with an edge. He titled his more aggressive project The Funky Headhunter. The first music video released for it was 'Pumps and Bump', and was banned from heavy rotation at MTV. Censors claimed that Hammer clad in just a Speedo bathing suit was too graphic; an alternate was filmed with Hammer fully clothed. He later released Inside Out in 1995; the album peaked at #119 on the Billboard charts, and received horrible reviews. He was dropped by Giant Records as a result.
Hammer's life of excess included: a $12 million house in Freemont, California, basketball courts, bowling alley, two gold plated 'Hammertime' gates for entrance to his property, a dishwasher in his master bedroom for his 'late-night snacks', 17 automobiles, 2 helicopters, a staff of 250, a paid entourage of 20, $1 million in thoroughbred race horses, antique golf clubs, and gold chains for his 4 Rottwiellers. Hammer eventually found himself $13 million in debt, despite his immense fortune that he had amassed, claimed bankruptcy on April 3, 1996. He admitted on The Oprah Wifrey Show that he had already spent his $20 million on an excessive lifestyle. Hammer rethought his lifestyle after hitting bottom financially, and was spiritually re-born as a Christian, and became an Ordained Minister.
Hammer enlisted in the Navy for three years, after he was unable to break into professional baseball.
Hammer's hit song "U Can't Touch This" was ranked #88 on VH1's 100 Greatest Dance Songs.
Hammer's nickname was derived from his childhood likeness to baseball legend, Hammerin' Hank Aaron. The Oakland Athletics referred to him "Little Hammer".