Elliott has spent two months with the Mariners, playing 11 games and scoring twice, but after limping out of Saturday's 5-1 win over Lincoln with a knee injury, the forward told Newell he would be heading back to the Championship side.
Newell told Grimsby's official website: "I had a word with Stuart and he said he's going back to Doncaster.
"We've thanked him, he's done brilliant for us. He's got a great attitude, he's very professional and we've got a couple of results with him in the side.
"When you weigh up how many wins we have had this season you've got to say that he's done well for us."