Clemens, a seven-time Cy Young Award winner and 11-time all-star, had last pitched for the New York Yankees in 2007.
In his 3 1/3-inning stint for the Atlantic League Skeeters, Clemens gave up only one single, to the Bridgeport Bluefish's James Simmons in the second inning, and no walks. He placed 24 of his 37 pitches for strikes with a top speed of 88 mph, recording two strikeouts.
Clemens didn't sound like a man intent on tacking on another year to his 24 seasons in the big leagues.
"My success tonight doesn't make me think about returning to the majors now," he said.
"Nothing was normal about this start. My main goal was not to embarrass myself or the ball club."
Clemens, who this year was acquitted on federal charges that he lied to Congress when he denied knowingly taking performance-enhancing drugs, received a standing ovation and waved to the crowd before leaving field.