Thomas inked a two-year, $1.55 million contract with Los Angeles on Thursday.
Thomas was reassigned to AHL Ontario on Tuesday.
Thomas was promoted from AHL Ontario on Sunday, Russell Morgan of Hockey Royalty reports.
Thomas was placed on waivers by the Kings on Sunday, per Chris Johnston of TSN.
Thomas (shoulder) practiced Thursday, Austin Stanovich of LA Hockey Now reports.
Thomas (shoulder) signed a one-year, two-way contract with LA on Saturday.
Thomas will undergo season-ending shoulder surgery after he was injured Saturday in AHL action, John Hoven of Mayor's Manor reports.
Thomas (undisclosed) was removed from injured reserve and sent down to AHL Ontario on Friday.
Thomas (undisclosed) will start the season on non-roster injured reserve, the team announced Tuesday.
Thomas (undisclosed) is listed with an injury ahead of training camp.