The highly competitive, 30 year old hooker will join the Exiles from Gloucester where he has made over 80 appearances in four years, scoring six tries. He joined Gloucester from Sale Sharks in 2008 and started his professional career with Glasgow Warriors.
Toby Booth, head coach at London Irish said: "Scott is an excellent signing for London Irish and will bring with him a wealth of experience. He is a reliable set piece operator and lively in the loose. He is a fantastic addition to our squad."
On his signing for the Exiles, Scott Lawson said: "I have thoroughly enjoyed my time at Gloucester and am sad to leave. However, I am delighted to be moving to London Irish, it's a great opportunity for me to progress my game further. Like Gloucester, their supporters are very passionate about their club and I am looking forward to be playing in front of them at Madejski Stadium next season."