The 21-year-old has risen through the ranks at the Hawthorns and although he is yet to make his first-team debut for the Baggies, he has enjoyed loan spells with Port Vale and Shrewsbury.
Sawyers is available to make his Saddlers debut in the Good Friday clash at Yeovil.
Boss Dean Smith said: "He's a young player who I have seen many times. He will strengthen us for the run-in to the end of the season and I am delighted that West Bromwich Albion have allowed him to come here.
"He's a talented lad who can play off the frontman and did well when he went on loan to Shrewsbury last season.
"I know that Albion rate him highly, so it's good to have him on board."