The 34-year-old Jonas Brothers singer filed to end his marriage with the 27-year-old star of Game of Thrones in Florida's Miami-Dade County Court.
The filing says "the marriage between the parties is irretrievably broken".
Turner and Jonas married in a secretive ceremony at a Las Vegas wedding chapel on May 1, 2019, after the Billboard Music Awards.
Country duo Dan + Shay performed at the wedding.
The couple had a daughter in 2020 and last year had another daughter.
Jonas is seeking joint custody of the girls, according to the divorce documents.
The two had a pre-nuptial agreement that Jonas expects will be enforced, according to the filing.
Representatives for Jonas and Turner did not immediately respond to requests for comment.
On Wednesday, Turner and Jonas each posted identical statements to their Instagram accounts.
"After four wonderful years of marriage we have mutually decided to amicably end our marriage," the statement read.
"There are many speculative narratives as to why but truly this is a united decision and we sincerely hope that everyone can respect our wishes for privacy for us and our children."
The couple said in interviews that mutual friends had long wanted to introduce them when they began talking via Instagram direct messages in 2016.
They met in person in October of that year and were dating each other exclusively by December.
They announced their engagement in October 2017.
Turner, who is from Northampton, England, played Sansa Stark for eight seasons on HBO's Game of Thrones and played Jean Grey in 2016's X-Men: Apocalypse and 2019's Dark Phoenix.
The Arizona-born Jonas came to fame with brothers Nick and Kevin in a band starting in 2005 and subsequent Disney Channel series.
They released their sixth studio album in May and are currently on a tour of US stadiums.
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