"A position within our squad became available because of injury and Scott is a high-calibre option to be able to bring in at this stage of the season," said Gloucester's head coach Dean Ryan.
"Our forward pack is a competitive area and Scott will only add to the depth we can select from. It is a great opportunity for both parties and I am really looking forward to seeing it progress over the coming months.
"It is extremely disappointing to lose a player like Ross but we have moved to replace him with a really good option."
Lawson moved to Sale from Glasgow Warriors 18 months ago and was part of Scotland's 2007 World Cup squad.
"To get an opportunity with a side like Gloucester is fantastic and I am just desperate for the chance to show them what I can do," Lawson said.
"This is a new chapter in my career and I am looking forward to it. Gloucester are regarded as a hugely go-forward and ambitious club and I want to help play my part in that quest for success.
"I have been given an opportunity by Dean Ryan and I will give it everything In can."