The Netherlands international reached the milestone during Tuesday's 3-0 Champions League victory over Aston Villa, coming off the bench in the second half after returning from a knee ligament injury.
De Jong had been sidelined for five months and missed the beginning of the season before making his comeback in the Clasico against Real Madrid on October 25. He has since featured against Alavés and Villa as he works towards full match fitness.
Speaking after the victory, the midfielder was keen to underline that he has put his injury problems behind him.
“I feel very good. Strong and with a lot of desire, very motivated. My knee isn't bothering me. What's happened has happened,” he said.
De Jong also acknowledged the scrutiny that tends to surround him, particularly when he is unavailable.
“There's always a bit of noise around me, especially when I'm not there,” he said. “Now I feel very strong, very fit. I have the feeling there's always more noise around me than around others.”
The 28-year-old also made clear that central midfield remains his preferred position, although he is prepared to help wherever Barcelona need him.
“That's where I feel most comfortable, but I will help the team wherever it needs me,” he said.
His comments come as he looks to re-establish himself in Hansi Flick's starting line-up. De Jong acknowledged that his recent absence means the coaching staff must manage his return carefully, but he is keen to play from the beginning.
The midfielder's 300 appearances have come since joining Barcelona from Ajax in 2019. He is now the club's most-used Dutch player, moving ahead of former team-mates and compatriots including Phillip Cocu and Ronald Koeman.
De Jong's immediate focus is on building consistency after his lengthy spell out. His latest performance and comments suggest he is ready to compete for a more prominent role as Barcelona move into the next stage of the season.