Sia’s about to face some stiff competition for Harry Jowsey — after she jumped into the battle early with a hand-holding stroll … he’s now getting ready to find a wife on TV.

Yup, you heard the right! Sia plugged the reality star’s new show, “Let’s Marry … Harry” on IG Monday morning by dropping a casting call for women to fight for his heart. Sounds like she’s ready and willing to compete, because she said she’s also signing up for the gig.

Now, no serious woman would want other gals eyeing her man, but with Sia pushing for more applicants, it seems their situationship was a clever stunt to promote the show — and it worked like a charm!

But hey, you’d be forgiven for thinking otherwise just hours earlier … when these two strolled out of an L.A. restaurant hand in hand, sparking a wildfire of dating rumors.