The blackout affected dozens of roads just south of Fratton Park, in the PO4 postcode area, beginning at Goldsmith Avenue, Southsea, and extending south to Brompton Road.
It was first reported at 5.30am, with engineers from Scottish and Southern Electricity Networks (SSEN) being scrambled to try and restore power.
It had been hoped that electricity would be restored by 4.30pm.
And for the majority of homes affected, it has been. However, there are still a number of homes in Bath Road, Jubilee Road, Francis Avenue, Delamere Road, Edmund Road, Wheatstone Road and Northcote Road that are still without power.
SSEN has warned residents still in the dark to expect power to be restored by 5pm.
In a statement on its website, the company added: ‘We’re sorry for the loss of supply. We currently have a fault affecting the areas listed.
‘If you need more information, please call us on 105, or send us a message on Facebook or Twitter (@SSENcommunity) and quote reference “JJ6748”.’