Macedonia international Popov has signed up for another year with the Baggies after Dinamo Kiev sanctioned a second season-long loan.
Popov said: "I'm happy to be back at West Brom. Last season I was a little bit late for pre-season because I was waiting for the deal to happen.
"This year it's good for me that I will be here for pre-season. This time I will start with the group and I'll be ready like everybody else.
"It's always good when you have competition. Liam (Ridgewell) is a good player and a good guy. I have a lot of respect for him."