Hooker Owens is a product of the Scarlets Academy and has gone to win plaudits on the international stage since making his regional debut against Northampton Saints in 2006.
The Carmarthen born star was made captain ahead of the 2014-15 season and will be looking to add domestic honours to his international achievements.
Owens, who has made 161 regional appearances, made his Wales debut against Namibia in the 2011 World Cup and won a grand slam on his way to back-to-back Six Nations championships in 2012 and 2013.
Full-back Williams has burst onto the regional and international scene in recent years with a string of no-nonsense performances. His recent success culminated with him being part of the Wales side that overcame South Africa in the final game of the Dove Men+ Care Series.
Scarlets Head Coach Wayne Pivac said: “Retaining players of both Ken and Liam’s experience and quality at the Scarlets is vitally important for the future of this region.
“Having experienced players, with great leadership qualities and genuine passion for our region, commit their futures to Parc y Scarlets reinforces our intentions and ambitions to compete on the highest level and continue to strive to reach our potential.”
The Scarlets travel to the Liberty Stadium for the first of two derby clashes with the Ospreys on Saturday December 27. The return leg at Parc Y Scarlets is set for January 3 with the Llanelli region sat seventh in the PRO12.
