Lawmaker Joseph Selasin of the opposition Chadema party says Tundu Lissu was airlifted to Nairobi early Friday.
Health officials in Tanzania’s capital, Dodoma, say Lissu was shot in the stomach, leg and arm on Thursday. Police are looking for multiple gunmen.
The attack has been condemned by both the opposition and the government.
Lissu, who heads the lawyers’ association in Tanzania, is one of the most vocal critics of President John Magufuli.
He recently was charged with using abusive language after he called Magufuli a dictator over alleged attacks on the opposition and the media.