"I did a lot of stuff in my past," Clark said tearfully at his plea hearing in Vermilion County Court Wednesday. "I have to own up to it."
Clark, 38, was the 13th pick in the 1998 NBA draft and had a six-year career with Denver, Toronto, Sacramento and Utah.
He has faced a series of criminal charges and has served multiple prison terms since his career in 2004, and dealt with alcohol abuse issues during his playing days, Sports Illustrated said.
In 2012, a sheriff's deputy found a loaded firearm in Clark's home, a parole violation, and earlier this year Clark admitted to having "too many beers" after driving his car into a telephone pole. He pleaded guilty to the two charges in two separate cases, and Wednesday was sentenced to four years for each count.