William has always worn his heart on his sleeve when it comes to his club allegiance and the Villa fan was watching on at Wembley in one of the upper boxes.
The second in line to the throne was sitting nearby Villa legend John Carew, who he embraced joyously after the final whistle.
Villa sealed their return to the Premier League after three years out with a 2-1 victory over Derby.
Goals from Anwar El Ghazi and John McGinn put the Villains 2-0 up, but Dean Smith’s side held out in tense conditions after Martyn Waghorn grabbed one back for the Rams.
Villa weathered the late storm, though, and ensured they will play top-flight football next season after three years in the second tier.
The Duke of Cambridge revealed his nerves ahead of the £170million match, telling BBC Sport last weekend: “I’m incredibly excited. It is going to be a bit of a nervy affair for me.”
It proved exactly that up until the final whistle, with William peeping through his hands as the clock ticked down in the final minute.
William’s presence in the upper stands of Wembley was unignorable and Aston Villa acknowledged the royal presence on their Twitter account after the game.
Speaking of manager Smith, they tweeted: “He led us back to where we belong, in front of royalty [crown emoji]. Arise, Sir Dean Smith! [love heart emoji] #AVFC”
William previously explained his allegiance to the Birmingham club in the side’s visit to Wembley for the 2015 FA Cup final.
“A long time ago at school I got into football big time,” he told BBC. “I was looking around for clubs.
“All my friends at school were either Man United fans or Chelsea fans and I didn’t want to follow the run of the mill teams.
“I wanted to have a team that was more mid-table that could give me more emotional rollercoaster moments. Aston Villa’s always had a great history.
“I have got friends of mine who support Aston Villa and one of the first FA Cup games I went to was Bolton v Aston Villa back in 2000.
“Sadly, Villa went on to lose to Chelsea. It was fantastic, I sat with all the fans with my red beanie on, and I was sat with all the Brummie fans and had a great time.
“It was the atmosphere, the camaraderie and I really felt that there was something I could connect with.”
Villa captain Jack Grealish was pivotal to the run which surged the side to the play-offs, and he was admittedly lost for words after the final whistle, having suffered heartbreak on the same stage last season.
Managing to string some sentences together, the 23-year-old said: “I’m speechless.
“It was such a hard game, but when I look around and I’ve got John [McGinn], Anwar [El Ghazi] – I believe.
“It means the world to go up, we know where this club belongs. I’ve stayed here and we’re back there now. I’ve led my boyhood team to the Premier League.