The highly decorated Olympian told German reporters on Friday that he will enter the Arena Pro Swim Series event in Mesa, Ariz.
"I've enjoyed lately, more than I really ever have, being back in the water," he said at a news conference in Munich. "I haven't had that kind of excitement ... in a long time."
Phelps retired after the 2012 London Olympics, then chose Mesa for his return last year. He was suspended last October.
He remains ineligible for the world championships this summer and has not yet committed to trying for the 2016