The 'Collide' star was joined by the German dancer and choreographer at the London event, which they watched from the front row.
Lewis teamed a floor-length, strapless, emerald green dress with a white blazer and gold clutch bag.
Also in attendance were singer Dionne Bromfield, Irish TV presenter Laura Whitmore and musician-turned-fashion expert Brix Smith-Start.
TV host and model Lizzie Cundy sparkled in a revealing number, while The Only Way Is Essex's Jessica Wright opted for a low-cut, long black dress.
Lewis, currently completing her forthcoming third album Glassheart, recently attended an Easter Open Day at Hopefield Animal Sanctuary in Essex, of which she is a patron and trustee.
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