The loved-up pair were seen hugging, and Cressida also leaned her head on his shoulder during parts of yesterday's event marking an initiative to empower young people across the globe.
The couple have been together for almost two years and reports recently suggested they might be about to move in with each other after Cressy was given the seal of approval from Royal security guards.
The 25-year-old former dance student was there to support her man as he took to the stage alongside the likes of Jennifer Hudson and Ellie Goulding and Malala Yousafzai.
Princess Beatrice, Richard Branson and son Sam Branson both made an appearance at the event, as well as Sam's wife Isabella Calthorpe, who also happens to be Cressy's sister. Confusing.
Cressy kept her style simple with a black jacket, a bright red shirt under a black sweater, black skinny jeans and metallic high tops.
Harry also kept it casual with a blue check shirt and jeans.
According to The Metro, Cressida playfully heckled Prince Harry when he took to the stage and joked and apologised to anyone expecting another famous Harry (Styles, fyi)
It's a rare public display of affection from the couple who were also pictured together earlier in the week as they left The Ivy.
Let's look back at Cressie's style...