Three Republicans crossed the aisle to seal her appointment by a vote of 53 to 47.
Justice Jackson's appointment fulfils President Joe Biden's campaign promise to put a black woman on the court.
Chuck Schumer, the majority leader, called it a "joyous day" for the US.
The vote was overseen by Vice-President Kamala Harris, the first black woman to hold the office.
Ms Jackson, 51, will replace Justice Stephen Breyer, a fellow liberal judge for whom she once clerked, upon his retirement in June.
