Prince Harry is a 'lucky man', says Meghan Markle's Suits co-star

Prince Harry is lucky man to be engaged to Meghan Markle, a co-star of the US actress says.

Britain's Prince Harry (L) poses with his fiancee, US actress Meghan Markle during a photocall after announcing their engagement in the Sunken Garden Source: AAP

Meghan Markle's Suits co-star Patrick J Adams says Prince Harry is "a lucky man" after the couple announced their engagement.

Adams, who plays Mike Ross, the love interest of Markle's character in the legal drama, posted a photograph of her on Instagram.

He wrote: "Playing Meghan's television partner for the better part of a decade uniquely qualifies me to say this: Your Royal Highness, you are a lucky man and I know your long life together will be joyful, productive and hilarious.

"Meghan, so happy for you, friend. Much love."

Patrick J. Adams as Mike Ross in Suits. Source: Suits

Earlier, Adams shared the engagement announcement tweet and joked: "She said she was just going out to get some milk..."

Ms Markle's on-screen father, actor Wendell Pierce, who plays tough-as-nails lawyer Robert Zane, also gave the couple his blessing.

He tweeted: "Congratulations to my TV daughter Meghan Markle and Prince Harry on the news of their wedding engagement.

"Harry you have her TV Father's blessing. Robert Zane approves @Suits_USA."

Gabriel Macht, who also stars in the series, tweeted: "Congrats to @meghanmarkle and Prince Harry.

"Sending all my best for your upcoming nuptials and a long happy life together. #love."

Markle, 36, has played Rachel Zane in the hit US television show since 2011.

In her first joint television interview with Prince Harry, she confirmed she is giving up her acting career.

"But I don't see it as giving anything up. I just see it as a change," she said.