The vow of poverty just wasn’t for her.

A crooked nun marked the start of Lent yesterday by pleading guilty to stealing more than $850,000 from a Catholic college in Westchester County.

Sister Marie Thornton, known around campus as “Sister Susie,” blinked back tears in Manhattan federal court while admitting she embezzled the money “for my own personal use” while serving as vice president of finance at Iona College in New Rochelle.

“At the time of my actions, I knew that my conduct was wrong and was illegal,” she said in a quavering voice.

Thornton, 63, entered her Ash Wednesday plea without cutting a deal with prosecutors, and she faces up to 10 years in the slammer when she’s sentenced in May.

Authorities haven’t said what Thornton did with the dough — which she swiped between 1999 and 2009.