Nestor Vidrio opened the scoring on the stroke of half-time in Apertura action at the Estadio Omnilife on Sunday.
Mexico U21 international Fierro was introduced in the 71st minute and made an immediate impact, doubling the hosts' lead four minutes later.
The result was put beyond doubt five minutes from time, when Fierro fired the ball into the roof of the net.
Guadalajara have collected nine points from seven games to sit 10th in the standings after ending their four-match winless run in the league.
Universidad Guadalajara remain second from bottom with five points.
‘Maybe I’ll be signed by Wrexham, who knows? English football would suit me – if an offer came, I wouldn’t think twice, I’d go immediately’ Euro 2024 cult hero reveals his UK dream
‘Managing Leeds? It was an option that appeared, but it wasn’t the right timing. I decided it wasn’t a good idea to leave the club I was at mid-season’: Premier League boss admits to turning down opportunity to replace Jesse Marsch in 2023
