Fukufuji, the NHL's first Japanese-born player, was lifted less than two minutes into the second period after Jim Slater's deflection gave the Thrashers a 3-1 lead. He stopped only 6-of-9 shots.
Los Angeles closed to within 3-2 when Tom Kostopoulos scored just over two minutes into the third. But Hossa, who will represent the Thrashers at next week's NHL all-star game, scored two more times to cement the victory.
Hossa has 29 goals for the season.
Shane Hnidy scored first for Atlanta, just 19 seconds after Alexander Frolov put the Kings ahead at 1:31 of the first. Glen Metropolit had the other goal for the Thrashers.
Kari Lehtonen stopped 28 shots for first-place Atlanta, which won its second straight game following five consecutive losses.
The Kings have lost five straight games.