The world's largest functional yoyo is 11 feet, 6 inches in diameter.
The massive toy was designed by a team at Bay College in Escanaba, Michigan. It took the seven members four months to perfect the behemoth, because it had to function like a normal yoyo in order to qualify for the world record. The test run went off without a hitch with the yoyo being dropped from a height of 90 feet! Somehow we doubt they were able to "walk the dog," though...
(source)
