Mitchell was part of a superb defensive unit that held firm against Manchester City's attack-minded team.
Despite conceding a penalty in the first half when Mitchell brought down Bernardo Silva on 36 minutes, his teammate Dean Henderson would not be beaten, saving superbly from Omar Marmoush.
The Palace wing-back then put in a number of timely blocks and crucial interceptions, particularly in the second half where the Palace backline seemed to grow in confidence.
"Yeah, it's a dream come true," he told Palace TV only minutes after the final whistle. "I don't know how to explain it. I don't know the feelings I'm feeling, but it's amazing.
"It hasn't quite sunk in yet, because we're still on the pitch. I don't know. I'm tired. But I feel like when I get home, it's really going to sink in.
"It's an amazing feeling. Not a lot of people get to play first team. Not a lot of people get to win trophies. So, I'm just blessed.
"It's amazing. I couldn't ask for a better day. Clean sheet, win, trophy, and then go home. I don't want to get too ahead of myself - but yes [qualifying for Europe] it's crazy.
"I'm not even trying to think about it too much, but it's a bonus to all the hard work this season."