Maricopa County prosecutors say 45-year-old Dumas entered his plea Thursday. He's scheduled to be sentenced Jan. 20.
Authorities say Dumas stole about $800 worth of merchandise from the Luke Air Force Base's exchange store while working with a janitorial service in 2012.
They say Dumas was seen on surveillance cameras taking cigarettes, alcohol, food, DVDs and shoes.
Dumas originally pleaded not guilty to eight felony charges of organized retail theft. He later reached a plea agreement.
Dumas played for the Suns from 1992 to 1995 and helped the team reach the NBA Finals in 1993. He was waived by the team after missing a drug test.