Ferguson was born in Nassau, Bahamas, but moved to the United States as a child, growing up in Cutler Ridge, Florida. Ferguson was raised with his two brothers by mother Rosemary Clarke. He went to Bel-Air Elementary School, where Ferguson was reportedly involved in his first fight at 13 as he tried to defend a friend. He continued his studies with Cutler Ridge Middle School and later with Richmond Heights Middle School. He attended Miami Palmetto High School, where he was the star middle linebacker. In 1992, his house in Perrine, Florida was destroyed by Hurricane Andrew, forcing him to live in his 1987 Nissan Pathfinder for a month.
In 2002, he was charged for carrying a concealed weapon and in 2003, he began his career in unsanctioned mutual combat street fights. They were distributed through the Internet, mainly through the adult website Sublime Directory and YouTube. In his first taped fight against a man named Big D, Ferguson left a large cut on his opponent's right eye which led Internet fans to call him Slice, becoming the last name to his already popular childhood nickname, Kimbo. His only on-tape street fight loss was against Sean Gannon, a Boston police officer who also trains in MMA. The popularity of the fight propelled both men into the MMA spotlight. On June 6, 2016, Slice was admitted to a hospital near his home in Coral Springs, Florida. He died a short time later. Details of his death are unclear, but foul play is not suspected. Scott Coker, CEO of Bellator MMA, confirmed the news in a statement: "We are all shocked and saddened by the devastating untimely loss of Kimbo Slice, a beloved member of the Bellator family."