According to Official Guinness Records,
The longest continuous moonwalk lasted for 2 hours 30 minutes 50 seconds and was achieved by Michael Frank (Germany) in Eppingen, Germany, on 30 Janurary 2011. Michael is a professional dance instructor and a national dance champion in Germany. He continuously performed Michael Jackson's iconic "moonwalk" dance move without pausing or taking a rest/bathroom break. At the end of the attempt he stated he could not feel the soles of his feet, but feeling was quickly regained.
For a complete list of 2011 records, please visit 2011 Guinness Records in Germany.