Members of Bolton Council's planning committee have granted consent for improvements to the town centre market on Ashburner Street.
The roofs on the fish market and western hall will be refurbished and a new roof put on the eastern hall, which houses the non-food section. There will be additional indoor food stalls and a seating area in the eastern hall.
The outdoor market will be moved to New Street closer to the planned new transport interchange.
Original plans which proposed a new entrance on the corner of Blackhorse Street and New Street have been revised as a result of discussions with existing market traders.
Work will start in February, with completion planned by late 2014. Indoor market traders, affected by the refurbishment, will be relocated temporarily to the current outdoor market in January.
Cllr Cliff Morris, leader of the council, said: "The market is one of our main shopping destinations and we have some of the best fish and fresh fruit and vegetables on offer in the region. The market will always remain a traditional home for traders selling all these goods.
"What the improvements will mean is that shoppers can buy the produce they do now but under a much better building."
Bolton Market opened in the 1930s and is one of Britain's oldest food markets. It has won a number of awards including Best Food Market in the BBC Radio 4 Food and Farming Awards 2011; Best Indoor Market 2010; and Tourism Retailer of the Year 2009. Up to three million people visit the market annually.