The Old Vic theatre in Waterloo has been granted funding of £5 million from the Department for Culture, Media and Sport, Arts Council England and Heritage Lottery Fund.
The Old Vic is one of 34 arts and heritage organisations sharing total funding from the £56 million scheme to support endowments.
The funding of £5 million is intended to hep the theatre raise an additional £15 million from other sources to put its future on a firm footing.
Applications were assessed by an independent panel chaired by Michael Portillo, and final awards made by the National Council of Arts Council England and the Board of Trustees of the Heritage Lottery Fund.
"Long term financial stability is an essential part of a successful cultural sector," said culture secretary Jeremy Hunt.
"With these grants, and the additional money they are bringing in, I'm delighted that we've been able to get a significant number of organisations on the road to long-lasting and sustainable endowments which will continue to support their work for years to come."
Michael Portillo said: "The advisory panel was impressed with the calibre of the applications we saw.
"I believe those we recommended for approval are well-placed to secure match funding from donors, and to build endowments which should strengthen their future financial resilience."