The ruling, spurred by a lawsuit from Hobby Lobby, picks at one of the mandates of the Affordable Care Act.
"No woman should have her health care decisions made by her boss. Period. This decision is wrong and a setback for women’s health," the governor said in a tweet from his official account.
His statement comes as O'Malley is contemplating a campaign for president and has laid some of the groundwork by visiting early primary states over the past few years.