The images show city worker Luke in a flat talking to Stacey's aunt Kat Slater (played by Jessie Wallace).
Matt, who currently stars in hit ITV drama Birds Of A Feather, confirmed his role in EastEnders in December, shortly after show bosses revealed that Lacey Turner would be making a return as Stacey.
Earlier this week, EastEnders teased a trailer of Stacey's return to Walford, in which Kat thinks she has spotted her niece from the top of a double decker bus.
Determined to find Stacey, Kat manages to track down her new address and discovers Luke in the flat with Stacey's daughter Lily.
But Kat is not sure if Luke knows Stacey's secret, after her niece fled the country with Lily three years ago when she was exposed as the killer of Archie Mitchell.
"Luke gives as good as he gets, so is a great foil to Stacey," said executive producer Dominic Treadwell-Collins. "Pity she's been lying to him since the day she met him…"
Last month, EastEnders revealed the first photos of Stacey, where she was snapped at the beauty salon with Kat.
Matt, who is married to Big Brother presenter and The Voice UK co-host Emma Willis, rose to fame in pop-rock group Busted.
The 30-year-old is now preparing to go on a UK arena tour in April as part of new super-group McBusted.
Speaking of his debut in the soap, Matt said: "I am so thrilled to be a part of such an iconic show. I grew up watching EastEnders, so this is really exciting for me!"
Watch the teaser clip of Stacey's debut below: