Manus Boonjumnong (Thai: มนัส บุญจำนงค์; RTGS: Manat Bunchamnong, born June 23, 1980) is a Thai boxer who won the Olympics at Light Welterweight (60–64 kg) at the 2004 Summer Olympics.

At the 2003 World Amateur Boxing Championships in his home town Bangkok, the light-footed counterpuncher won the bronze medal losing to Russian Alexander Maletin.

He narrowly defeated reigning 2005 world champion Serik Sapiyev at the tournament although he was knocked down.

In Chicago at the 2007 World Amateur Boxing Championships, he was upset early against Japanese Masatsugu Kawachi.

In Athens he beat reigning world champion Willy Blain and the Cuban Yudel Johnson in the final and won gold.