McMullen, a former Brumbies representative, has signed on for one year and will be joining former Tigers team-mate Peter Short at the club.
The 29-year old fly-half-cum-centre will be used as cover for fly-half Cedric Rosalen, and has seen his chances of game time at Leicester limited by their signing of Italy star Ramiro Pez, as well as the presence of Sam Vesty and Austin Healey at the Welford Road outfit.
