Potts underwent a medical yesterday afternoon after an undisclosed fee was agreed between the League One promotion-chasing Reds and Preston, who had been tracking the 24-year-old for some time.
The figure eclipses the previous record fee of £1.5m that North End paid to sign then Manchester United striker David Healy in December 2005.
Barnsley are understood to have a future financial interest in Potts, who joined the club from Blackpool just before the start of the 2017-18 season, signing a three-year deal.
Chief executive officer Gauthier Ganaye said: “We have made a significant profit on this transfer, which brings long-term sustainability to the club and allows us to reinvest short-term in the squad.
“We have also kept an interest in Brad’s future (and) he now leaves with everyone’s genuine best wishes.”
Already this month the Reds have reportedly rejected two offers for forward Mamadou Thiam – one from a Championship club and the other from a Ligue 1 side in France.
In other developments at Oakwell, Barnsley have completed the permanent signing of Fulham striker Cauley Woodrow following an initial loan spell, while forward Tom Bradshaw has sealed his full-time move to Millwall after spending the first half of season on loan with the Lions.
Woodrow, who has firmly endeared himself to the Oakwell faithful in scoring seven goals in 14 appearances after being sidelined with injury earlier this season, has signed a two-and-a-half-year contract, with a further year’s option.
While the news regarding the full-time addition of Woodrow has been greeted as a welcome move by Reds supporters, the sale of Potts will be viewed as a disappointing and potentially worrying development to many.
Speaking to the press ahead of tomorrow’s FA Cup tie at Premier League outfit Burnley, assistant head coach Andreas Winkler stressed the importance of the Reds keeping their squad together during a potentially definitive second half of the season as the club seek an instant return to the Championship.
The League One promotion chasers are six points adrift of second-placed Luton Town with a game in hand.
Daniel Stendel’s side has gained significant momentum following a strong haul of 11 points from five games against sides towards the top end of League One and confidence abounds that a concerted push for the top-two can materalise in the new year if the squad stays together.
Winkler said: “At the start of the season we only signed three players and only lost Tom Bradshaw. This was our plan – that every player in the squad can show his performance and how he can adapt to our philosophy.
“But we want to build a strong squad with a good mentality. It would not be good if we lose too many players.
“Every club wants to sign new players to strengthen the team. But on the other hand a good team sticks together with a good mentality.
“If you look at our pitch on the training ground we have fun together and work really hard. If we make too many changes it will not be good.”
Meanwhile, the Reds, who take on Burnley in a lunchtime kick-off tomorrow, will assess midfielder Callum Styles over the coming weeks before deciding whether he will remain at Oakwell for the rest of the season or be loaned out once again.
The 18-year-old was immediately loaned back out to League Two Bury for the first half of 2018-19 after Barnsley bought him for a significant undisclosed fee from the Shakers in August.
Winkler, who confirmed that top-scorer Kieffer Moore is available for tomorrow’s Cup tie, said: “Callum will train with us for two or three weeks and we will have time to decide what is best for the player and team.
“I think he has improved a lot and adapted to adult football and he has played from the start for Bury for the last three matches.”
Meanwhile, the Reds’ assistant insists that all the pressure will be on top-flight Burnley in the third-round tie at Turf Moor.
Tomorrow marks the fifth anniversary of the last occasion that the Roses pair met in the competition with Barnsley triumphing 1-0 at Oakwell, thanks to a late goal from Danny Rose.
On the task facing the Reds, who will be backed by a sell-out travelling contingent of 2,500, Winkler added: “I think the pressure is on Burnley. We are focused on League One and the pressure is on them especially at home.
“We have a young squad with high pace and I think we can be good competitors.
“We will not be arrogant, but we have enough confidence. There is the basis to be successful.
“We will not be nervous. It is not Liverpool or Manchester United, but we have lots of respect for a Premier League team like Burnley.
“Both teams want to get into the next round and maybe face a very famous team. It is much more than a test.”