Thobela first made international waves in 1990 by securing the WBO Lightweight Title against Mauricio Aceves. His victory and subsequent title defenses twice underscored his prowess in the ring. However, significant bouts marked both his successes and setbacks. In 1993 he faced Tony Lopez and initially lost, only to claim victory in their rematch, demonstrating his resilience.
His career faced turbulence when he encountered back-to-back losses to Olzubek Nazarov in 1994 and suffered a notable upset against Karl Taylor the same year. These defeats hinted at an emerging decline as Thobela struggled with maintaining competitive form and weight.
Despite these challenges, Thobela experienced later success by winning the WBC Super Middleweight Title in 2000 against Glenn Catley. Unfortunately, he could not hold onto this title for long, losing it during his first defense match. His career ended with him losing seven consecutive fights before retiring in 2006 with a final record of 40-14-2.
Apart from his official matches, Thobela's career also witnessed moments of controversy. A noteworthy incident occurred just before a fight against Mads Larsen in Denmark in 2003 when he abruptly left post-weigh-in upon reportedly being overwhelmed by Larsen's condition.
Though remembered for this controversial overseas incident, Thobela's legacy is better encapsulated by his earlier achievements more than the hardships that shadowed his later years. While remembered for various reasons—both victories and defeats—his time as a competitive force at lighter weight classes stands out as most remarkable.