Leeann Waldron, 25, was last seen in her car in Harrogate town centre, at about 2pm yesterday (Tuesday).
Police say the mum-of-two's disappearance is "extremely out of character".
She has not had any contact with family, friends, or her children.
A spokesperson for North Yorkshire Police said: "Officers are becoming increasingly concerned for her safety and would appeal to anyone who has seen Leeann, or knows of her current whereabouts, to contact police."
Anyone with information is asked to contact police on 101, quoting reference number 1217209396, or 999 with immediate sightings.