The result keeps La Fiera perfect at home this season, while the Tuzos remain winless in the Clausura 2020.
In the 9th minute, Pachuca was forced into an early substitution after Luis Chávez was injured, and things never improved from there. León was in complete control of the run of play and in the 14th minute, they took the lead through Ángel Mena, whose shot from outside the box beat Alfonso Blanco to make it 1-0.
Just five minutes after that, Blanco brought down Ismael Sosa in the box and León was awarded a penalty kick. Leonardo Ramos stepped up to take it, and he converted it to make it 2-0 for the hosts.
Pachuca had very few chances to reduce the deficit, and when they did create a rare opportunity, León defended well to keep them off the board.
At the other end, León continued to attack and they always looked likely to run up the score. In the 55th minute, Luis Monte played in William Tesillo, who finished off the service to make it 3-0 for the hosts.
Pachuca looked to inject some energy by bringing on Eugenio Pizzuto in the 59th minute, but just nine minutes into his debut he suffered a gruesome-looking injury that Pachuca later reported to be a broken fibula and dislocated ankle, which the midfielder will undergo surgery for.
That cast something of a pall over the rest of the game, which Pachuca had to see out with 10 men as all three of their subs had been used.
They never came close to reducing the deficit, while León several times could have added a fourth goal.
With the 3-0 win, León reaches six points while Pachuca still has one.