Bifouma spent the second half of last season on loan at West Brom, scoring on his debut in a 3-1 defeat at Crystal Palace in February.
The 22-year-old finished the campaign with two goals from six league appearances, but will now resume his career in Spain.
Almeria confirmed his arrival on Friday, with the deal including an option to sign Bifouma on a permanent basis.
"This signing was a big goal for us," club president Alfonso Garcia told the official website.
"This is one of the players that impressed me most in the Mediterranean in recent years."
Bifouma, meanwhile, is pleased to have secured a move away from Espanyol, who fined him earlier this month after the striker failed to return to training on time.
"This has been a difficult summer for me and I have lived an uncomfortable situation with Espanyol, but also very nice because I found a good place to practice my profession," he said.
"I'm still not 100 percent, having some physical problems after being with the selection of the Congo and working on artificial grass, but I hope to be ready for the first game of the season.
"I come to work and give everything to achieve the goals with Almeria."
