The winger, Vinicius Jr, found the net twice within the opening 10 minutes, establishing control for Carlo Ancelotti's side in Saudi Arabia.
Although Robert Lewandowski pulled one back for Barcelona with a superb volley, Vinicius extended Real Madrid's lead with a converted penalty in the 39th minute, maintaining their two-goal advantage.
In the second half, Rodrygo added a fourth goal before Ronald Araujo's red card compounded Barcelona's misery.
Vinicius, who recently returned from a hamstring injury in November, marked his opening goal celebration with Cristiano Ronaldo's famous 'SIU' inside Al Nassr's King Saud University Stadium, where the former Real Madrid player currently competes.
Vinicius stated, "The celebration was dedicated to Cristiano Ronaldo, because he is my idol and now he plays here."
The victory marked Madrid's third consecutive win in El Clasico and secured their 13th Super Cup success, just one behind Barcelona's record of 14 wins.
Jude Bellingham played a crucial role in the opening goal, providing a well-timed pass behind Barcelona's high line for Vinicius to capitalize on and round goalkeeper Inaki Pena.
Rodrygo continued the onslaught, perfectly timing his run behind the defense, crossing for Vinicius to slide in at the back post.
Barcelona responded with Alejandro Balde's cross finding Lewandowski, who thumped in a first-time finish from the edge of the box.
Shortly thereafter, the referee awarded a penalty as Vinicius was allegedly brought down by Araujo while attempting to connect with a cross. Despite protests from Barcelona, the 23-year-old Brazilian confidently converted the spot-kick, completing his second hat-trick for Madrid.
As Barcelona pushed forward in the second half, Madrid exploited the counter-attack, and Rodrygo capitalized on defensive errors to score the fourth.
Barcelona's situation worsened as Araujo received a second yellow card for a foul on Vinicius with 20 minutes remaining.
Despite Madrid's attempts to secure a fifth goal, Bellingham's shot was cleared off the line, and Barcelona avoided further punishment in the closing stages.
Xavi, Barcelona's manager, admitted, "We have not shown the level required for a match like this. We played our worst game. We weren't comfortable at any point. Madrid hurt us on the counter. I apologise to the fans because it was hard for us to compete and we showed our worst side."
