Barca's 2-0 win at Espanyol, with Fermin scoring on the night, confirmed them as 2024/25 champions.
He said afterwards: "We're really happy. We've achieved our goal. We've worked hard to get here, and we deserved it.
"Today makes up for the disallowed goal from the other day. It's served to give us peace of mind."
We weren't insulting anyone
Fermin was also asked about taking their title celebrations off the pitch, with Espanyol turning on the sprinklers as the away team partied.
He said, "The coach is happy. He's guided us the whole way, and it's time to be happy and celebrate.
"I understand that after what happened last time, it's normal to go to the locker room. But we're not hurting anyone; we're celebrating the league title, and we haven't disrespected anyone. We went inside as quickly as possible."
Fermin added, "I remember my family, my girlfriend, the people who have always been there for me. It was a dream to win titles with the club of my life. We're going to celebrate for sure. I'm not tired."