The talented and hugely experienced centre returns to the starting XV for the region's monumental clash against the Scots, at the Parc, after a lengthy period on the sidelines due to a hamstring injury received in the season opener against Ulster.
King will be joined by Gareth Owen at inside centre while Harry Robinson and flying Fijian Michael Tagicakibau add power and pace out wide.
Young fullback Steff Evans has been rewarded with the 15 shirt after strong and solid performances against Zebre in the last round of the PRO12, and Northampton Saints and Cardiff Blues in the LV= Cup.
The halfback pairing of Aled Davies and Steven Shingler pick up where they left off in the home victory over Zebre earlier this month where Shingler kicked seven penalties and a conversion in atrocious weather conditions.
John Barclay adds weight to the back of the scrum and will also lead the Scarlets against his former side. Joining him in the backrow will be Aaron Shingler and James Davies.
The region's return to Guinness PRO12 action will also see Shingler senior make his 100th appearance for the Scarlets on Friday evening.
The South African pairing of George Earle and Johan Snyman pack down at second row whilst tighthead prop Peter Edwards adds experience and maturity to the youthful front row pairing of Rob Evans and Kirby Myhill.
Scarlets Head Coach Wayne Pivac said: "Zebre was a valuable victory for us and the next two weeks are very important for us. The extend squad is very, very, important to us here, particularly whilst the international campaign is running.
"We've had a squad training for this game since last week whilst the LV= Cup was running and the boys who have put the work over the last week and more get the start with the internationals adding impact off the bench.
"It's great to have Regan back in the side as a player of his quality in the ranks as he lifts the boys around him.
"Glasgow have been playing an expansive game, they have made more passes than anyone else in the league, scoring a lot of tries and their defensive work has been very good.
"They'll be a tough nut to crack and it's a very big game for us. We understand the importance of these games come the end of the season and we'll be hoping for a decent result."
Scarlets team v Glasgow, Friday 20th November kick-off 7.35pm at Parc y Scarlets;
15 Steffan Evans, 14 Harry Robinson, 13 Regan King, 12 Gareth Owen, 11 Michael Tagicakibau, 10 Steven Shingler, 9 Aled Davies, 1 Rob Evans, 2 Kirby Myhill, 3 Peter Edwards, 4 George Earle, 5 Johan Snyman, 6 Aaron Shingler, 7 James Davies, 8 John Barclay ©
Replacements: Emyr Phillips, Phil John, Jacobie Adriaanse, Rob McCusker, Rory Pitman, Rhodri Williams, Rhys Priestland, Steffan Hughes
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland