Born and raised in Chicago, Walker was a wrestling fan as a child and whose favorite Wrestlers included Hulk Hogan, Ric Flair and The Road Warriors (Hawk and Animal). He also often went to events at the Rosemont Horizon. Attending North Park University, Walker graduated with a bachelor of science and a degree in exercise physiology as well as having an athletic career competing in college football, baseball and wrestling. He also competed in amateur bodybuilding during college, winning second place in the 2002 and 2003 Mr. Illinois competition.
In 2003, he began training to become a professional Wrestler. His trainer Eric Priest was himself trained by independent Wrestlers Danny Dominion and Ace Steel. Prior to his debut, he had a brief stint with the National Indoor Football League playing for the Myrtle Beach Stingrays. Following his debut, Walker wrestled throughout the United States both under his real name and as Mike Venom, winning numerous championship titles on the independent circuit as well as facing his boyhood idols The Road Warriors in several tag team matches.
Walker joined World League Wrestling soon after his debut and took part in the Harley Race–Pro Wrestling Noah training camp during 2005 and 2006. On September 24, 2005, Walker scored one of his first major victories defeating Kenny Omega, later aired by Pro Wrestling Noah on Japanese television, and feuded with WLW Heavyweight Champion "Wild" Wade Chism. At the end of the year, he lost to Chism in a three-way mach with Brutus "The Barber" Beefcake on December 10, 2005. The following month, the title was held up, in part to interference by the villainous Referee Trevor Murdoch, during a match between the two in Eldon, Missouri on January 28, 2006. On February 24, Walker lost a 3-way dance when Jason Bates was pinned by Chism in St. Joseph. The next night however, Walker was pinned by Bates in a second 3-way dance with Chism to win the title.
In November 2006, he signed a World Wrestling Entertainment developmental contract and assigned to Deep South Wrestling and Florida Championship Wrestling before being released from his contract the next year. Since then, he and Rasche Brown have been competing as the SkullKrushers, and currently hold the record for the longest reign as NWA World Tag Team Champions.
On October 27, Walker made his return to World League Wrestling defeating Derek McQuinn for the WLW Heavyweight title in Waterloo, Iowa. On November 9, Walker also defeated Dinn T. More for the AWA-Brew City Wrestling Heavyweight Championship. The next night at the NWA Pro Wrestling Summit in Hammond, Indiana, Walker lost to Misterioso. On November 24, he lost to AAW Heavyweight Champion Jerry Lynn at an All American Wrestling event. He also teamed with Dan Lawrence to defeat Derek St. Holmes, Kris Hybrid and Bonebreaker Brooks on December 15, 2007.
At an event for Brew City Wrestling, he and Skullkrusher fought to a double-countout on January 12, 2008. He lost the WLW Heavyweight title a little over three months later to "The Masterpiece" Chris Masters on February 9 in Fordland, Missouri. On March 29, Walker lost to reigning AWA Superstars of Wrestling United States Championship Ricky Landell in an "MMA vs. Wrestling" match to crown the first WSL Fighting World Champion. Following this match, the United States title was abandoned. He later teamed up with Rasche Brown, formerly known as Skullkrusher, to form the Skullkrushers. On October 4, the Skullkrushers defeated Los Luchas to win the NWA World Tag Team Championship. Walker again defeated Landell on February 21, 2009 in Michigan City, Indiana to win the Wrestling Superstars Live World Heavyweight Championship. On November 20, 2010, Walker and Brown lost the NWA World Tag Team Championship to The Dark City Fight Club (Kory Chavis and Jon Davis), ending their reign at 778 days.
On April 14, 2010 the team of Keith Walker and Bison Smith defeated Takeshi Rikio and Muhammad Yone to become the GHC Tag Team Champions in Osaka. On August 31, however, Walker's father died. He later chose not to immediately return to Japan, and on September 10 he and Bison Smith were stripped of the GHC Tag Team Championship.