Former Liverpool and Real Madrid midfielder Alonso, who said in March he would retire when his contract ended, also ended a memorable career in both domestic and international football.
His triumphs include two Champions League wins, four domestic titles, including three with Bayern, as well as the 2010 World Cup and the 2008 and 2012 European Championships with Spain.
A trademark diagonal pass from Alonso allowed Arjen Robben to cut inside from the right flank and open the scoring against Freiburg, before second-half goals from Arturo Vidal, Franck Ribery and Joshua Kimmich sealed the win.
Alonso was brought off in the 81st minute to another emotional standing ovation from the Bayern fans.
“Alonso is one of our best signings of recent years, a real lucky find, a gifted tactician, a highly intelligent man and one of the most uncomplicated players I’ve ever witnessed,” added Rummenigge.