"Britain should be playing a leadership role to bring about a ceasefire in the conflict, not taking instructions from Washington and putting British military personnel in harm's way", Corbyn continued.
"The government appears to be waiting for instructions from President Donald Trump on how to proceed, but the US administration is giving alarmingly contradictory signals. But the US administration is giving alarmingly contradictory signals", he said, calling for the government to press for an independent UN-led investigation of the chemical weapons attack in Syria.
Mrs May doesn't have a majority in Parliament, but the Democratic Unionist Party, which is propping up her government, said it backed her actions.
"Cabinet agreement" was not "sufficient for action", he said.
"This legally questionable action risks escalating further, as United States defence secretary James Mattis has admitted, an already devastating conflict and therefore makes real accountability for war crimes and use of chemical weapons less, not more likely", he warned.
He added: 'Theresa May should have sought parliamentary approval, not trailed after Donald Trump.
United Nations fails to adopt Russian draft resolution on Syria
Russia vetoed a US text, while two Russian-drafted resolutions failed to get a minimum nine votes to pass. Seven no votes resulted in this proposal being rejected, three of which were from permanent members.
The Douma attack has drawn global outrage which has seen the Prime Minister and Mr Trump agree that the use of chemical weapons must not go unchallenged after Mrs May won the backing of her Cabinet for action to prevent their further use in Syria. "Parliament must consider evidence, objectives and vote".
"They agreed that the Assad regime had established a pattern of unsafe behaviour in relation to the use of chemical weapons".
Over the past few days, divisions have begun to emerge within the main political parties.
"Liberal Democrats stood ready to assess the evidence and objectives for any action and, if it were properly planned and justified, to support a military response". Writing in the Guardian on Thursday, Conservative MP Bob Seely, a former soldier, warned military intervention carried profound dangers.
Stop the War, a pacifist coalition once chaired by Corbyn, has called a demonstration outside the British parliament on Monday to protest against the strikes. An inquiry whose findings were made public in 2016, led by Sir John Chilcot, concluded that Britain had chosen to "join the invasion of Iraq before the peaceful options for disarmament had been exhausted".
Earlier, Mr Trump appeared to row back from a suggestion on Wednesday that missile strikes were imminent, insisting in his latest tweet that he had never set out a timetable for military action.