Rafael Cavalcante tests positive
California State Athletic Commission executive officer George Dodd confirmed Cavalcante's test result with MMAFighting.com.
The CSAC has not disclosed which banned substance was found, but it has suspended Cavalcante for one year and fined him $2,500.
Cavalcante becomes the third former Strikeforce champion to test positive for a banned substance this year.
The CSAC suspended former women's featherweight titleholder Cristiane Santos for one year and fined her $2,500 in January after a prefight urine test came back positive for stanozolol metabolites.
As a result, Santos' victory over Hiroko Yamanaka on Dec. 17 was changed to a "no-contest."
Former light heavyweight champ Muhammed Lawal was suspended and fined by the Nevada State Athletic Commission in March.
He tested positive for anabolic steroids following a second-round stoppage of Lorenz Larkin on Jan. 7. The outcome of that bout also was changed to a no-contest.
Cavalcante defeated Kyle by first-round submission in a 205-pound title elimination bout.