Chloe Jeffreys was reported missing from Crawley in West Sussex yesterday.
She is believed to be with her one-year-old daughter.
Officers launched a search for the pair after they were last seen in Worthing.
Police have stated that they are “concerned” about the disappearance.
Chloe has been described as 5ft 7ins tall, slim, and with long red/burgundy hair.
She is wearing black leggings, a black top and black and burgundy trainers.
Her daughter has blonde hair and is understood to be wearing a pink fleecy zip-up cardigan and is in a black iCandy push chair.
Sussex Police said: “Police are concerned for Chloe Jeffreys, who was reported missing from Crawley on Thursday (November 10).
“If you see them or have any information that could help, please call 999 immediately, quoting serial 477 of 10/11.”