Guilherme Mendes is a four-time IBJJF black-belt World Champion at featherweight (−64 kg). Under Ramon Lemos he won Worlds gold in 2009, 2011, 2012, and 2014, earned Pan gold in 2013, and with brother Rafael helped popularize the berimbolo before co-founding Art of Jiu-Jitsu in Costa Mesa.

He retired from competition in 2015 and was inducted into the IBJJF Hall of Fame in 2022. His teaching focus on retention, berimbolo mechanics, and long-term development connects directly to open-guard, De La Riva, and back-control pages.