The Homeland star was the guest of honour at Queen Elizabeth II's royal residence, where he was recognised for his services to drama.
He was given the award by the monarch's son, Charles, Prince of Wales - and Harewood is overjoyed with the accolade.
The actor showed off his medal on British TV show Daybreak on Thursday (16Feb12) and added, "I'm really really proud of it."
Harewood admits he was initially unaware he'd been tipped for the honour, as he didn't open the official notification for days.
He says, "I completely didn't expect it. I thought it was a tax bill so I didn't open it for three days. Brown envelopes for me cause fear, it's always a serious letter, so I don't open them and I left it there (for days)."