Barca say the agreements for the new deals have been reached "following weeks of negotiations" as the club seeks ways to reduce their wage bill in light of the financial problems caused by the coronavirus pandemic.
The Blaugrana announced losses of €97 million for the 2019-20 season earlier this month and revealed that the club's debt had more than doubled to €488m, all while trying to manage a wage bill of around €500m.
"The new terms include a temporary salary adjustment due to the current circumstances brought about by the Covid-19 induced crisis," a club statement explained.
ESPN first revealed last week that goalkeeper Ter Stegen had agreed to extend his stay at Camp Nou until 2025. His release clause has been increased to €500 million.
Pique, meanwhile, has prolonged his deal by a further two years until 2024, although the new terms are subject to him making a certain number of appearances throughout the 2021-22 season. His release clause remains fixed at €500m.
Finally, Lenglet and De Jong have both put pen to paper on new deals until 2026, with their release clauses standing at €300m.
Sources explain that the "temporary adjustments" mentioned by Barcelona mean the quartet have accepted reduced salaries this season to allow the club to temporarily cut the wage bill with revenue down due to the pandemic.
However, they will be remunerated in the latter years of their contracts.
The announcement comes as Barca push ahead with plans to introduce wage cuts across the club. Negotiations are due to take place on Wednesday in a bid to reach an agreement on further salary reductions for playing and non-playing staff.
Having signed new deals, Pique, Ter Stegen, Lenglet and De Jong will now be exempt from those negotiations.
Sources have told ESPN, though, that the first team players will not have a representative present at Wednesday's talks. They are willing to give up part of their salaries but are not happy with the way the board of directors have conducted themselves.
It's the latest example of the growing rift between the players and the board room.
President Josep Maria Bartomeu's future is hanging in the balance as he tries to force through these changes to improve the club's financial situation.
But he could be out of a job next month with a vote of no confidence against him expected to be held within the next two weeks. If 66.6 percent of eligible voters among the club's membership vote against him, he will be removed from his position and elections called to elect a new president.
Regardless of what happens with the vote of no confidence, Bartomeu has already entered the final months of his mandate and elections have been scheduled for March.