A group calling themselves OurMine claimed responsibility for the hack after posting a series of messages on Twitter and Facebook.
The group have previously taken over the accounts of a number large companies including the Twitter accounts of Netflix, Marvel, WWE, HBO and Playstation.
FC Barcelona's accounts on Twitter, Facebook and all other platforms have been hacked
In one post the signing of PSG winger Angel Di Maria was 'announced' on the club's Twitter and Facebook timelines.
"Welcome Angel Di Maria to FC Barcelona #DiMariaFB," the post read, before being deleted.
Even FC Barcelona's Facebook account has got hacked.
A tweet reading "Let's get #FCBHack trending on Twitter" then appeared before Barcelona regained control of the accounts.
"Our accounts have been hacked tonight. We're working to solve the problem as soon as possible. Thanks for your patience," the club tweeted.
The hack comes less than 24 hours after Barcelona announced they would be suing Neymar for alleged breach of contract.
Our accounts have been hacked tonight.
We’re working to solve the problem as soon as possible.
Thanks for your patience.— FC Barcelona (@FCBarcelona)
The Catalan club are looking to recoup £7.8m from the Brazilian, who joined PSG in a world record move earlier this month.
The club are also demanding the return of a loyalty bonus paid after he renewed his deal in October, less than a year before he signed for Paris St-Germain
"FC Barcelona has sent the Spanish Football Federation the labour lawsuit against Neymar Jr they submitted on 11 August at the Labour Tribunal in Barcelona so that they can pass it on to the appropriate authorities in the French Football Federation and Fifa," a club statement said.
"In the lawsuit, the Club demands the player return the already paid sum for his contract renewal as he has not completed his contract; €8.5 million in damages; and an additional 10 per cent because of delayed payment. The Club also requests Paris Saint-Germain take on responsibility for the payment of these fees if the player cannot do so himself.
"FC Barcelona has started these proceedings to protect its interests following Neymar’s decision to buy out his contract just months after he signed an extension until 2021. This legal defence will be carried out following the established procedures with the competent authorities without entering into any verbal arguments with the player."
Neymar had previously criticised the Barcelona board in an interview following his PSG debut on Sunday evening.