A 75th-minute penalty from David Nugent gave champions Leicester a 1-0 win and relegated Doncaster to League One.
Pearson said: "I was very pleased because when you have achieved all the goals you want to achieve before the end of the season, there is not a lot of pressure on us.
"But for us to go out there today and finish in front of our own fans with a positive result and the added benefit of being one of the few sides to go beyond 100 points, is a great achievement.
"People talk about us romping to the title. But it hasn't always been that. We have had to work hard.
"We came up against a side today who wanted to keep it tight and that gave you an indication of how the tactical side of the game panned out.
"I am very disappointed for Paul because of what happened elsewhere but we've got a job to do and I thought we deserved to win the game.
"Clearly for us the next step for this club's development is to try and establish ourselves as a Premier League side.
"That's not the easiest thing to achieve but we have a group of players here who I think will do well with a few additions.
"It is not going to be a case of rebuilding or a major overhaul. There are not going to be huge changes in terms of the playing squad. We just need to get the additions right to what we have got."
The win was City's 31st of the season and took them to a record 102 points.
Doncaster boss Paul Dickov promised that every effort will be made to win instant promotion back to the Championship.
Rovers came into the match with a game plan designed not to concede a goal, and it seemed to be working well enough - until the penalty incident.
Goalkeeper Sam Johnstone kept them in the game with some fine saves, three of them from Nugent, but could do nothing about the striker's spot-kick that was blasted into the roof of the net. It was Nugent's 20th league goal of the season and his 22nd in total.
The penalty was awarded by referee Paul Tierney after James Husband had sent Riyad Mahrez sprawling with a clumsy challenge.
Doncaster might have snatched an equaliser in the 79th minute when Paul Keegan had a chance from the edge of the penalty area - but he blazed his shot high over the bar and Birmingham's dramatic draw at Bolton meant Rovers were relegated.
After the Football League Championship trophy had been presented to Leicester, a bitterly disappointed Dickov said: "Obviously we are gutted and disappointed because it was everyone's aim this year to keep us in this division.
"It is not all about today though. We can look at the result today and results elsewhere, but it's over the course of the season.
"And more often than not you probably deserve to be where you are at the end of the season.
"We came up a little bit short but it wasn't through lack of effort from the players, the club or the fans.
"We gave it everything we had. I thought we were resolute today in what we wanted to do. We knew we had a job to do and tactically for the majority of the game the players did it well.
"But once we gave the penalty away and you hear scores coming from elsewhere you want to try and get attacking players on the pitch. It was difficult when Birmingham equalised as late as they did.
"The one thing I do now is pick myself up, pick the club up and we go again next season.
"If I had managed to keep the club up today it would have been the biggest achievement of my career.
"Will I be manager next season? Absolutely. We have had conversations before today and the club want me to stay. All our efforts now are to make sure we get promoted next season."