According to Official Guinness Records,
The most spins on a unicycle in one minute is 131 and was achieved by Satomi Sakaino (Japan) on the set of Kinsma, at the TBS Broadcast Center in Akasaka, Tokyo, Japan, on 19 November 2011.
Satomi Sakaino is a professional unicycle rider and performs with her sister. She is touring America for 2 years with the Cirque du Soleil to perform their unicycle acts (until the year 2013).
For a complete list of 2011 records, please visit 2011 Guinness Records in Japan.