The "Ghostbusters" star, who is known for his love of sports, was spotted in the stands at the Amway Center in Orlando, Florida, heavily applauding the Xavier Musketeers as they faced off against the University of Maryland's Terrapins, who were the favourites to advance to the second round of the US college basketball play-offs.
However, the Musketeers, whose assistant coach is Bill's son Luke, managed to pull off an upset, defeating their rivals 76 to 65, much to the actor's delight, reported Contactmusic.
They are also parents to another son, named Homer, while the 66-year-old has four other boys with costume designer Jennifer Butler, who he divorced in 2008 after 11 years of marriage.
Bill isn't the only celebrity parent to get emotional during the start of the so-called March Madness season.
"Seinfeld" star Julia Louis-Dreyfus also celebrated as her sports ace son Charlie Hall helped lead her alma mater, Northwestern University, to the second round.