The superstar made a dramatic entrance at her appearance in the capital's Westfield shopping centre in Stratford.
Rihanna rocked an androgynous look with a matching blue and grey striped trouser and top, complete with electric blue oversized blazer.
The Barbadian star added a pair of grey pointed court shoes and sunglasses rimmed in a matching hue to her blazer to finish off her statement look.
Rihanna's signature scarlet lipstick and a dramatic Mohican hair style added impact.
Earlier in the day the star hinted at her blue outfit by tweeting an excited alert to her British fans:
"Uk navy! I'm turning on the Christmas tree lights at Westfield Stratford City in London, be there at 4pm!, (sic)" Rihanna tweeted.
Rihanna later performed at an exclusive mini-gig in front of 20,000 fans in London as part of her 777 Tour.
The 24-year-old changed into a white two-piece number with a tie waist detail and an outline handprint for her secret performance.
The unusual outfit had a retro feel and Rihanna added chunky gold jewellery and a crop top underneath for extra '80s effect.
Rihanna was visited backstage at the gig at The Forum in Kentish Town, London, by singer Kylie Minogue and British model Cara Delevingne. Cara walked the Victoria's Secret Fashion Show with Rihanna two weeks ago.
The star has been making headlines with her tour wardrobe over the past few days.
On Sunday she took to the stage in Berlin, Germany, wearing a black mesh top with controversial white marijuana leaf print, thigh-high black leather boots, a white satin coat and leather shorts.
"We were in and out of Berlin in a mad heartbeat," Rihanna's stylist Mel Ottenberg told Vogue.
"Loved this look in the industrial club she played: oversize shirt by KTZ, mesh top by Love Leather, shorts by Adam Selman, boots and sunglasses by Tom Ford. After the show we hung out backstage for a while then on to London at 4.00 am for TWO shows the following day."
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