Pearson took charge at Derby in October 2007, ending his time as chairman of Hull City.
His surprise exit at Pride Park came on a day of speculation at his former club - the Tigers were forced to deny manager Phil Brown had been sacked. BBC Radio Humberside reported on Wednesday night that the Tigers chairman Phil Duffen had left the club and Pearson was set to return.
"I have enjoyed my two years at Derby despite not achieving the playing success we had hoped for," said Pearson in a statement.
"Under [manager] Nigel Clough's management the wage bill is now under control, the squad size is under control, the Academy structure is solid and we have a management team in place who will take the team forward."
The FA are awaiting the report from a crowd control advisor from Barnsley's loss to Manchester United as well as from referee Chris Foy after eight fans were arrested at the match.
It has been reported that eight catering staff were trapped inside a food kiosk and had to barricade themselves in a store room as fans broke in and stole cash from the till and food from the shelves.
Stewards on the pitch also had food thrown at them during United's 2-0 victory.
An FA spokesperson said: "There is no place for anti-social or violent behaviour in our game.
"Any culprit found to be involved in these disturbances and identified as such by
either the police or clubs should be subject to a lengthy ban from attending football matches."
Barnsley have accused Manchester United fans of causing 'substantial damage' to Oakwell.
Mark Robins, the Tykes manager, felt that his side lacked belief to try and cause an upset.
The Red Devils ran out 2-0 winners despite the home side carving out a number of openings against the Premier League champions.
Robins said : "If you look at the stats we had 17 efforts on goal and you'd be hard-pressed to find any side that creates that many chances against a Manchester United side.
"On the downside we haven't taken any and you've got to take your chances. I just felt we were lacking that bit of belief. There's more in there for us. There's more in the players, so there are positives."
Derby County have extended the loan stay of Fulham defender Fredrik Stoor by a further two months. The Sweden international, 25, has spent the past month at Pride Park.