Stormont ministers gave the go-ahead for the ambitious infrastructure projects during their weekly Executive meeting.
The £150 million transport route will run from the east to the west of the city and so link two areas traditionally divided on religious grounds.
The £100 million Titanic Signature project will be located on the same site on which the famous White Star Line vessel was built almost 100 years ago by Harland and Wolff shipyard workers.
It is hoped the five-storey Titanic centre will be open to the public ahead of the centenary of the boat's sinking in April 1912.
The Executive is providing half the funding with a range of other stakeholders, including Belfast City Council, contributing the other £50 million.
Work on the rapid transit system is set to get under way in 2011 and one of its stops will be at the new Titanic centre, which is on the east side of Belfast Lough.
Ministers had rejected proposals for a full tram network on cost grounds, with the rapid transit system described as being a "tram on wheels".
The Titanic project will not get the official green light until the other stakeholders formally sign up, but First Minister Peter Robinson said he was satisfied that their agreement would be forthcoming.