24-year-old Rawlins' rugby career started in the centre with hometown club Caerphilly and is the latest addition to the 2015-16 season with confirmation earlier this week that George Earle has extended his contract with the region and young Tom Price making the move from Leicester Tigers.
An inevitable move into the second row due to his stature and a season with Cross Keys saw him picked up by Llanelli RFC before signing a development contract with Scarlets ahead of the 2012-13 season. His versatility in open play sees him slot just as comfortably into the backrow.
Son to former Cardiff RFC lock Peter Rawlins, who himself made 129 appearances for the capital city club, Lewis has this year made strides in Scarlets colours with 15 appearances, including four in European Rugby Champions Cup.
Scarlets Head Coach Wayne Pivac said; "Seeing young developing players like Lewis move on to full senior contracts is a huge boost for us as a region. Lewis has made real strides this season and has offered us a strong option both at lock and backrow.
"At only 24 years of age, and still quite new to the game and his position, Lewis has plenty more developing to do as a player and is a very exciting prospect for us going forward."
Speaking about the news Rawlins said: "I'm enjoying playing rugby for the Scarlets at the moment. Wayne [Pivac] has given me an opportunity and I've got a bit of confidence from that.
"There's tough competition in the squad but I'm happy to keep working away, continue to learn from more experienced players around me and continue to do my best for the region."
Rawlins is the latest player to extend his contract with Scarlets' ahead of season 2015-16 alongside Liam Williams, Ken Owens and Rob Evans who have all penned new contracts with the region. Rhodri Jones, Samson Lee, Jake Ball and Scott Williams all also set for a bright future at the region on National Dual Contracts. Amongst the new names added to Scarlets' squad are Glasgow and Canadian winger DTH van der Merwe, outside half Aled Thomas, tighthead prop Will Taylor from Wasps and lock Tom Price from Leicester Tigers.