Martin, who won his first MotoGP title last season with Pramac Racing, switched to Aprilia on a two-year deal, but the 27-year-old has yet to score a point this year after seven rounds.
Wrist and ankle injuries sustained in a pre-season crash prevented him from competing in the first three rounds before a crash in his first race in Qatar led to a collapsed lung and bruised ribs, which have kept him off the bike for weeks.
"When I made the decision to change manufacturers last year, one of my premises was to have the possibility to test the bike in real circumstances and to understand the team and its working methodology," Martin said in a statement.
"In this way I could feel comfortable signing for two years instead of one, and so we included that condition.
"Faced with the situation of having to make a decision on a date that is established by contract, I have decided to exercise my right to release myself for the 2026 season."
Aprilia said last week that they had not had any negotiations with Martin to change his contract and allow for an early exit while also warning other teams not to approach him.
The Italian outfit said they expected Martin to see out his contract until the end of 2026 but the 27-year-old said he was "taking control of my future as a professional athlete" and that there was no conflict.
Professional athlete
Martin said he was taking control of his future as a professional athlete.
"At no time have I ever breached the contract. When we signed it, I agreed with Aprilia that, if certain circumstances were not met, I reserved the right to decide my future for 2026," he added.
"This was an essential condition for me to accept the contract proposal they offered me at that time."
Without Martin, Aprilia have struggled for results but finally won a race this season when Marco Bezzecchi triumphed in the British Grand Prix on Sunday.
After the victory, which came after race leader Fabio Quartararo retired with a technical issue, Aprilia CEO Massimo Rivola said: "This is a message for Jorge, our bike can win."
However, Martin remains unconvinced they can compete in the long run and will look for another manufacturer by the end of the season.
Martin was in the running last year for a factory Ducati seat, which went to six-time MotoGP champion Marc Marquez, who leads this year's championship with 196 points.
Martin completed only 13 laps in pre-season testing and retired from the only race he competed in after the crash in Qatar.
"Unfortunately, the circumstances that have occurred as a result of the crashes, although it is true that they do not affect what we agreed, have conditioned this phase," Martin said.
While the door to Ducati may be closed and KTM are also struggling for results, Honda could offer him a seat, especially after Luca Marini sustained severe injuries in a testing crash. The Italian's contract runs out at the end of the season.