Twenty-five-year-old Holmes was arrested Tuesday night along with former Brooklyn Nets forward James Webb III after authorities say the found a recently used marijuana joint inside their vehicle.
Both men posted bond soon after being booked into a Miami jail.
Holmes became an unrestricted free agent this summer and averaged 8.2 points and 4.7 rebounds per game this past season.
He's the second Suns player to be arrested in South Florida this month after swingman Josh Jackson was detained when police say he refused to leave a music festival VIP area he had entered without a pass.
It wasn't immediately known whether either man has a lawyer.