Abigail Peckham, aged 33, is from Bursledon but was last seen at around 7.30am in the Fawley area.
According to police, she was driving a black Volkswagen car with the number plate ending HTY.
In their appeal, the force described has as being white with an olive complexion, 5ft 5ins tall, with long black hair which was tied in a bun when she was last seen.
She was also last seen wearing a multi-coloured onesie body suit with a long cream jumper and cream sandals. She also has a full arm tattoo sleeve on her left arm.
A police spokesman said: “We are growing increasingly concerned for her welfare.
“If you think you’ve seen Abigail since she went missing or think you know where she is now, please call us immediately on 101 quoting 44230294803. In an emergency dial 999.”