The 37-year-old shook hands on a four-year deal with the Ibrox hierarchy late on Thursday in London - with the announcement coming on Friday afternoon.
It will be Gerrard's first attempt at senior management having coached Liverpool U18s for the last year.
"I am honoured to become the next manager of Rangers," said Gerrard. "I have enormous respect for this football club, and its history and tradition.
"I can't wait to start this new journey at Rangers as we look to build on the many successes that this club has achieved."
Former Scotland international Gary McAllister will be his assistant at Ibrox, Sky sources say.