Thompson made his professional debut on January 27, 2000, defeating DeShaun Harper by majority decision. He earned $300 for his first fight, which allowed him to cover household electric bill that month. In the early years of his professional career, Thompson was still doing regular 9-to-5 jobs alongside boxing, as Thompson viewed boxing as a source of a supplemental income. He often trained in the gym early in the morning before the start of a full work day. By Thompson's own admission, he soon started viewing boxing as something more than "just a side gig" after piling up a couple of wins: "I won a couple of fights, but I knew I could be a lot better". On May 20, 2001, Thompson faced local hard-hitting prospect Chester Hughes, who had 9–0 record (6 KOs) coming into the bout. It was the first fight in which Thompson faced someone who was both taller and had longer reach than himself. He won the bout by first-round TKO.