The West Ham player failed to impress during his loan at the Ricoh Arena last season and has joined for a month.
Scunthorpe boss Ian Baraclough told his club's official website about Sears: "He has looked stronger and quicker than ever, and has been firing for their reserves. "We're taking a lad out of reserve team football into first team football and we don't want to put too much pressure on him, but he's a player who will enhance our squad and hopefully he will help the lads up front by chipping in with a couple of goals."
Speaking about the move, Sears, who was also on loan at Crystal Palace last season, said he had spoken to Jordan Spence who had also been on loan at Glanford Park: "I spoke to Spence, and he said it was a good club. He had a really good time here and I hope I have as much fun as he did.
"I've seen Scunthorpe play a couple of times and watched how Gary Hooper did last year, he got a lot of goals. I've got a lot of pace and am able to run in behind defenders.
"I can play up front and on the wing too, so anywhere that the gaffer needs me really."
Sears is expected to be included in Scunthorpe's squad to face Preston tonight.