Naomi Lee, 40, had last been seen on CCTV on Tuesday (September 21) at the Post Office in Theatre Street, Preston.
Lancashire Police said they had been "very concerned for her welfare" and had appealed for the public's help in finding her.
She had been missing for nearly three weeks and was last seen in person on Sunday, September 5.
But today, the force shared the good news that Naomi has been found safe.
A police spokesman said: "Good news, further to our earlier appeals, Naomi, 40, missing from Blackpool, was found by police in Preston yesterday (Thursday, September 23).
"Thank you to everyone who helped share our appeals to find her."