Lori Loughlin is pulling the plug on her marriage to Mossimo Giannulli ... filing for divorce after nearly three decades together.

The "Full House" star has filed paperwork, months after the longtime couple separated and began living apart.

Lori listed the date of separation as August 31, 2025. She noted they signed a prenup and said they will figure out support at a later date ... she also noted they have irreconcilable differences.

They tied the knot in 1997 and share daughters Olivia Jade and Bella Giannulli.

Their split has already come with some big financial questions ... TMZ previously reported Lori signed a prenup before the marriage that could leave their assets largely separate, and the pair also sold their Hidden Hills mansion for $12.65 million late last year.

The divorce makes their breakup official after a very public marriage that survived the college admissions scandal, prison time and plenty of fallout.

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Lori also made her return to Instagram in the past week ... posting Monday a video captioned, "Here's to things working out."

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