Lion Capital has appointed bankers to offload its majority stake in the restaurant business with hopes to fetch between €240m to €300m, according to The Sunday Times.
The move could secure a hefty windfall for Lion, which bought the business for around €120m in 2005.
Wagamama management could also be in line for a bumper haul if they sell their minority shareholding.
Wagamama, which employs around 2,300 staff in the UK, has rapidly grown in the last five years, now totaling 66 British outlets and 39 international restaurants.
Operating profits leapt 75% to €8.5m in the year to April 2009, while sales rose 13% to €121m, according to the most recent set of available accounts.
Lion has already tried to cash in on its investment under plans to float Wagamama in 2007, but pulled the proposals due to wider stock market woes as the credit crunch took hold.
It is thought that Lion will begin the formal sale process next month, with hopes to sell the business by the end of 2010.
Hakkasan restaurateur Alan Yau founded Wagamama in Bloomsbury, London, in 1992 to offer pan-Asian food in an informal canteen setting.
It has since expanded across the UK and US, with a franchise operation in countries spanning Europe, the Middle East, Australia and New Zealand.