The 23-year-old openside was born in England but raised in Australia, going on to represent England against the Barbarians last month after impressing for Bristol, despite them finishing bottom of the table last season.
Bath Director of Rugby Jack Rowell said of Lipman's signing: "Adam Vander, who had an outstanding season for us, is currently sidelined with a serious foot injury and the latest prognosis is that he will not be available for us until late autumn if his rehabilitation goes well.
"Therefore Michael, along with promising England Under-21 international James Scaysbrook, will be vying for a place in a strengthened back row next season."
Lipman added: "I am excited about the prospect of joining one of the most prestigious clubs in England and can’t wait to play at the Rec.
"I am also looking forward to playing with a number of the internationals in the Bath pack and am excited about the challenge ahead."
Lipman joins a Bath side who narrowly avoided the drop last season, but have made a host of personnel changes going into the new campaign.
Props David Flatman and Duncan Bell have joined in the pack from Saracens and Pontypridd respectively, as has hooker Christian Balshen from Swansea.
Gloucester lock Rob Fidler and back rower Jonathan Pettemerides have further strengthened the scrum, while London Wasps scrum-half Martyn Wood and Bristol centre Andy Higgins have added pace to the backs.
By Mark Smith