Tia Mowry is pulling the plug on her marriage ... filing for divorce from her husband of 14 years, Cory Hardrict.

According to legal docs obtained by TMZ -- The "Sister, Sister" star filed docs in Los Angeles on Tuesday -- citing irreconcilable differences as the reason for the end.

Tia -- who is being repped by Disso Queen Laura Wasser - didn't specify a date of separation, but she's asking a judge for joint physical and legal custody of their two children. She's also asking the judge to terminate the court's ability to give spousal support to either ... and notes the couple has a prenup.

Tia and Cory tied the knot back in 2008 and they currently have 11-year-old Cree and 4-year-old Cairo together.

She took to Instagram Tuesday and shared a cryptic message, which seemingly had something to do with the divorce. It reads, "Letting go can be painful. But it won't hurt as much holding on to an illusion."