Wigan's relegation to League One has been confirmed after they lost their appeal against a 12-point deduction for going into administration.
Wigan appealed against the punishment on the grounds of 'force majeure'.
But an independent arbitration panel ruled against them, meaning Barnsley will stay in the Championship.
The Latics went into administration on 1 July when their new Hong Kong-based owners conceded they could not support the club financially.
Force majeure events are usually defined as certain acts, events or circumstances beyond the control of the involved parties, such as natural disasters, war or a pandemic.
The timing of Wigan going into administration meant their penalty was applied following their 1-1 draw with Fulham on the final day of the season.
Without the punishment the Latics would have finished 13th in the table, but once the points were deducted they ended up second-from-bottom.
Wigan said: "The club put forward a strong case and naturally we are disappointed at the decision. The first-team management will now prepare the team for next season's League One campaign."
Assistant manager Leam Richardson will take charge of the team when they return to training next week after Saturday's resignation of boss Paul Cook.
In a statement, the English Football League added: "The decision of the arbitration panel is final and legally binding.
"The EFL will continue to engage with the administrators to provide its full support in all ongoing matters with the aim of achieving a long-term future for the club."
Latics' impressive form proves in vain
Wigan's relegation will feel particularly cruel to their fans as it comes after their side produced a remarkable run of form in a bid to avoid the drop.
The Latics won eight, drew six and lost just one of their final 15 games of the season, but with their points deduction enforced, finished 23rd, two points from safety.
That ends their two-year stay in the Championship, after they won the League One title in 2018.
The club's relegation is their third from the Championship in the space of six seasons - all of which saw them finish 23rd.
And it is the fourth time they have suffered a relegation in their past eight campaigns, including 2013's drop from the Premier League, which ended their eight-year spell in the top flight.
How did the Latics get here?
4 June: A takeover of Wigan Athletic by Next Leader Fund is completed. The limited partnership is headed by Hong Kong businessman Au Yeung Wai Kay. Au Yeung says he is "excited to join the Wigan Athletic family" and looks forward to supporting the club "in what is going to be an initially challenging period".
1 July: The Latics enter administration, becoming the first English professional club to do so since the coronavirus pandemic began, and the EFL say the club are to be deducted 12 points. The sanction is to be applied to 2019-20's league table if Wigan finish outside the bottom three after their regulation 46 league games.
7 July: Administrator Gerald Krasner says the club have appealed against their 12-point deduction.
14 July: Wigan record a stunning 8-0 win over Hull City, moving 12 points clear of the drop zone in the table, prior to any points deduction, boosting their survival hopes.
18 July: Paul Cook's side concede a stoppage-time equaliser in a 2-2 draw away at relegation rivals Charlton, in the penultimate game of the campaign, damaging their chances of escaping the drop.
22 July: The Latics draw 1-1 with promotion-chasing Fulham on the final day of the Championship season and the result is not enough to prevent them from dropping in to the relegation zone at full-time when their 12-point penalty is applied. They slip from 13th to 23rd, two points from safety.
1 August: Manager Cook resigns from his position "with a heavy heart".
4 August: Wigan's relegation is confirmed after their appeal against their 12-point deduction is dismissed.
Why was Wigan's sanction enforced this season?
On 31 July, an independent disciplinary panel deducted 12 points from Sheffield Wednesday for the 2020-21 season, after the Yorkshire club were found to have broken spending rules.
If the Owls' points deduction had been imposed for this season - like Wigan's - then they would have finished bottom of the Championship and been relegated, giving 22nd-placed Charlton a reprieve.
However, unlike the Latics' administration, Wednesday's case was a disciplinary matter.
The EFL added: "In cases of insolvency, the panel does not determine the timing of the sanction as it can in independent disciplinary proceedings."
Wigan's relegation ensured 21st-placed Barnsley will play in the Championship for a second consecutive season.
The Tykes' owner Chien Lee said on Twitter: "Barnsley finished a remarkable turnaround season and stay at the Championship, we fought on the field and off the field, we fought with the coronavirus, we never give up, thank you to our supporters."