Rodrygo scored twice before the break to give the hosts a comfortable lead. Later in the second half, goals from Asensio and Karim Benzema helped them seam the victory.
After winning LaLiga, Carlo Ancelotti has become the first coach in history to win titles in all five major European leagues.
Additionally, Carlo Ancelotti won the Premier League with Chelsea, the Serie A with AC Milan, the Ligue 1 with Paris Saint-Germain, and the Bundesliga with Bayern Munich.
After beating Espanyol now Real Madrid will now have all their attention focused on the second leg of their semi-final against Manchester City on Thursday.
Real Madrid lost their first leg 4-3 at the Etihad Stadium and now they will face Manchester City at the Santiago Bernabeu on May 5th.