The actor, who already is father to 11-year-old daughter Isan, is best known for his roles as detective Luther and gangster boss, Stringer Bell in The Wire.
The happy couple were pictured grinning at the Harper’s Bazaar Women of the Year awards at Claridge’s Hotel in London earlier this week.
A friend commented, “Idris and Naiyana are so in love and this is the icing on the cake for them.
“They had been keeping it quiet as it’s early in the pregnancy, but they’ve told family and friendsand Naiyana is beginning to show.
“She is absolutely lovely and she’s looking radiant. Her and Idris are a great couple and feel lucky to have found each other.
“Obviously Idris is a bit of a TV heartthrob so Naiyana is the envy of women across the country.
“But the truth is Idris is the one who really considers himself the lucky one. He’s a great dad and she’ll be a brilliant mum. They can’t wait for their new arrival.”
We’re so happy for you both, but do we send a Pink basket or a blue basket to congratulate you?