Hannah, 35, was snapped on the red carpet at this year's Everyday Heroes event and she looked barely recognisable from her pop star heyday.
Sporting a short platinum hairdo, Hannah wore a long black dress to the ceremony, which she teamed with seriously thick eyeliner and a splash of red lipstick.
The star, who was pictured on the red carpet at London's Grange St Paul's Hotel, carried a silver clutch bag and accessoried with simple silver earrings.
Hannah found fame aged just 18 after landing a place in S Club 7, alongside Rachel Stevens, Tina Barrett, Paul Cattermole, Jo O'Meara, Bradley McIntosh and Jon Lee.
The group starred in their own TV series, Miami 7, and enjoyed a string of No 1 records before disbanding five years after they had formed.
Since the group's split, Hannah has focused on her acting career, landing roles in Primeval, Death In Paradise and more recently Casualty.
In 2014, S Club 7 reunited for Children In Need.
Watch an S Club 7 throwback here!