Ken Owens will play his first game since September in Scarlets' LV Cup match with London Irish on Saturday.
The Wales hooker had to undergo surgery on a disc in his neck and his return will boost Wales for the Six Nations opener with England on 6 February.
Scarlets also welcome back veteran prop Phil John after a knee injury.
"It's a huge boost to have Ken and Phil back; they bring a lot of experience and it's going to help our young props," coach Ioan Cunningham said.
Owens, 28, took over from the injured Richard Hibbard on Wales' two-Test series against South Africa in June, scoring a try in the 31-30 second Test defeat.
However, the 26-times capped hooker missed the entire November international series following his injury, with Hibbard and Ospreys hooker Scott Baldwin selected.
Former Exile Steve Shingler makes only his second start of the season at outside-half and will be partnered at half-back by Rhodri Williams.
Scarlets' new signing Jack Payne will take his place on the replacements bench and will be hoping to make his regional debut at Parc y Scarlets.
The 6ft 5in, 18st 3lb back-row, who can also play lock, has played for Australia Under-20s but is Wales qualified.