The actress has been snapped at beauty salon Beauty, formerly named Booty, in Albert Square alongside Kat Moon, played by Jessie Wallace.
BBC One tweeted the photo, saying: "Look who's back on the set of #EastEnders!"
Last month, Lacey confirmed that she was returning to EastEnders after leaving the BBC1 soap three years ago.
Her character Stacey will arrive back in the Square with a new city slicker boyfriend, played by McBusted star Matt Willis.
Announcing her return, Lacey said: "I may have left EastEnders over three years ago, but the show has always been in my heart - as has Stacey - and she has never really left my side.
"I am so excited about returning and seeing what the future holds for her. It's been a while since I set foot in Albert Square and I am looking forward to coming home."
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