Former Pussycat Doll Nicole is a global ambassador for the Special Olympics, and Lewis thanked his girl for bringing him along to the dinner celebration to mark the sport organisation's 46th anniversary.
Lewis wrote on Instagram today (4 August): "I had the pleasure to go to the White House & meet the president of the United States & 1st lady thanks to my lady @nicolescherzy, thank you.
"I'm proud of you babe for being the global ambassador for the special Olympics #specialolympics #honour #1stblackpresident #obama."
In a collage of photos posted on Lewis' Instagram page, the blissfully happy couple can be seen joining hands at the dinner table.
In another snap, 'Your Love' singer Nicole affectionately leans her head on Lewis's shoulder for a selfie - aww!
Formula One ace Lewis and former X Factor judge Nicole, who recently celebrated their six-year anniversary together, also cuddled up to music legend Stevie Wonder for a photo!
Also in attendance was tennis ace Andy Roddick with wife Brooklyn Decker and popstar Katy Perry, who performed in a sparkly midnight blue gown.
After the dinner, Lewis and Nicole made the most of their night by visiting some cultural landscapes.
"Got to see Washington DC a little, hanging out with president Lincoln, what an amazing city," said Lewis. "To stand where Dr Martin Luther King did his big speech, amazing! #DC #lincoln #goodtimes."
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Watch Nicole's video for 'Your Love' below: