Maggie Grace quietly pulled the plug on her marriage many months ago ... 'cause TMZ has learned the "Lost" actress secretly filed for divorce from husband Brent Bushnell last year.

According to legal docs, obtained by TMZ, Maggie filed a petition to dissolve the couple's marriage in Washington state in May 2025, stating the marriage is "irretrievably broken." The filing says she and Brent actually began living in separate households in October 2024.

The docs show the couple already worked out many of the details before heading to court, referencing both a premarital agreement and a property settlement and separation agreement signed in March 2025.

According to the petition, neither Maggie nor Brent are seeking spousal support. Maggie is also asking the court to restore her legal name to Margaret Grace Ives. Brent signed the joint petition as well, signaling the divorce appears to be uncontested.