The midfield general began his rugby career with Ruthin at the age of six and stayed with the club until the age of 18 when he left for the University of Bath. Whilst playing for the University side, Higgitt was spotted by Bristol Rugby and was signed to Bristol's Under 21 side.
The 28-year-old power packed centre, who can also play wing, went on to make 111 appearances for Bristol Rugby between 2002 and 2008 and scored 20 tries.
Welsh-born Higgitt, who also played for Caerphilly and Ebbw Vale, moved to Llanelli Scarlets in 2008 and spent two years with the Welsh region, memorably scoring the final try at Stradey Park in October 2008.
Higgitt, who was part of the Scarlets team that defeated Warriors in the LV= Cup last season, captained Llanelli on several occasions and made a total of 28 appearances in Wales.
"Rob is the ultimate professional and one of the most dedicated players I've ever had the pleasure of working with so I'm delighted he will join us at Warriors for next season," said Richard Hill.
"He is extremely focused and someone that other players look up to because of his work ethic and superb attitude. Rob literally eats, breathes and speaks rugby.
"Rob is also the master of defence and when I worked with him at Bristol we used the blitz defence to really press teams. He was our leader who set the example for others to follow.
"I know Rob really well after working with him throughout my time at Bristol, I saw him develop in the Championship and become a really top Premiership player. Every season he plays with confidence and looks to prove himself again, that is exactly the type of character I want at Warriors."