They went public with their relationship last year after friendship turned to romance.
And David Foster, 68, and Katharine McPhee, 33, enjoyed a rare red carpet appearance at Elton John’s annual Academy Awards Viewing Party together in Los Angeles on Sunday.
The actress and singer stunned in a semi-sheer black gown, which gave a peek at her lingerie.
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The American Idol star cut an elegant figure in the jewel encrusted gown which featured ruched detailing at the front, including a butterfly design.
The brunette’s sleek tresses were pulled back into a tight bun, and she styled a few locks of hair at the front so that they fell across her face.
Katherine brushed on glamorous make-up that perfectly suited her outfit for the night, as her smokey eye shadow made her brown eyes shine.
David looked dapper in a navy blue suit, which he wore over a crisp white shirt.
Despite being more than twice her age, David and Katharine looked smitten as they posed together at the event.
The pair were both seen alongside a cast of celebrities, including Lionel Richie, 68, and his youthful girlfriend Lisa Parigi.
Lisa slipped her enviable frame into a black velvet dress, which was cut low in a cleavage-boosting design.
After working the red carpet, Katharine rubbed shoulders with Nicole Scherzinger, 39, who looked a vision of beauty in a stunning black one-shouldered gown.
The songstress showcased her ample assets as well as teasing a glimpse of her
Katharine was also seen with Glee star Lea Michele, who sizzled in her black and gold gown which featured a deep-plunging neckline and dangerously high thigh slit.
Both David and Katherine have had musical careers – as David is a business mogul in the industry and Katharine starred and sang on the TV show Smash.
Next month, she will begin playing Jenna on New York’s Brooks Atkinson Theatre in the hit musical Waitress, marking her first Broadway gig, Playbill reported.
David has in his time gone through four marriages – to singer B.J. Cook from 1972-1981, to Rebecca Dyer from 1982 to 1986, to songwriter Linda Thompson from 1991 to 2005 and to model-turned-reality-star Yolanda Hadid from 2011 to last year.
His split with Yolanda went public in 2015, but the divorce was not finalised until 2017.
Katharine and her own ex-husband, producer Nick Cokas, tied the knot in 2008.
But in October 2013, McPhee was photographed kissing her married Smash director Michael Morris.
By May 2014, Cokas and his wife publicly announced their intention to dissolve their union, and the divorce was finalised in February of 2016.
David has sired eight children, whereas Katharine has none at present.
She revealed to La Palme recently: ‘My ideal situation, I would love to get married and have kids, it would be nice if that happens.’
However, in January E! News quoted a source saying: ‘David has not shown any interest in getting married again.
‘He hasn’t discounted how he feels about Katherine but there are no plans for them to even get engaged anytime soon.’