Specsavers' six-figure sponsorship deal will also see the UK's leading opticians' logo emblazoned on match officials' shirts, perimeter boards and media backdrops at each club.
Specsavers' continued support for the Magners League has enabled Celtic Rugby to raise standards in refereeing.
This season, for the first time, TV Match Officials and Citing Commissioners will be used to aid referees and punish violent conduct. This, allied to the Specsavers Fairplay League, is aimed at encouraging greater discipline, transparency and accountability in the game.
Specsavers founder Doug Perkins said: "Rugby has always been a great passion of mine, so Specsavers is delighted to be extending our sponsorship to the Magners League. Having grown up in Wales and played rugby for Llanelli, I still follow the game.
"As opticians, we understand that vision is vital to good sportsmanship and our sponsorship will help to ensure our refs are seeing clearly - something that is sure to resonate with the refs and fans."
He added: "As with any sport, referees can win and lose matches and it will be interesting to see how the introduction of TV match officials will develop the fair play of the sport. Our Specsavers Fairplay League, which will be run in conjunction with the match points table, will be a great way of encouraging this and putting something back into grassroots rugby."
David Jordan, director of Celtic Rugby, commented: "We're delighted that Specsavers have signed up for another two seasons and are enhancing it with the Specsavers Fairplay League. It shows that the Magners League is in good health and is continuing to improve.
"Match officials have a tough job and we hope that with Specsavers' continued support, we can make it easier for them on and off the pitch."