Spears was invited to appear by Kim Cattrall (right)
Spears' character will take after Jones - played by Kim Cattrall - as a man-eating seductress, stealing her aunt's lover.
It will be the second time Cattrall and Spears have appeared as screen relatives recently after Cattrall starred as Spears' mother in the pop singer's new film, Crossroads.
Cattrall invited the singer to star in the New York-based TV show after filming Crossroads, and the results will be broadcast later this year.
Spears tries to cultivate an innocent image in real life, but has taken risqué roles in Crossroads and Sex and the City.
The New York Post newspaper quoted an insider on Sex and the City as saying: "Samantha thinks her niece is a virgin, but nothing could be further from the truth."
Sex and the City has won fans and awards for its upfront portrayal of the exploits of thirty-something women in Manhattan.
Poor reviews
Spears has also been seen in sex scenes in Crossroads, her debut movie which opened at United States cinemas at the weekend.
But it got poor reviews from critics and was beaten to the top spot in the US box office chart by Denzel Washington's new drama John Q.
In Crossroads, Spears' character, Lucy, embarks on a voyage of discovery with school-friends and loses her virginity while on a journey across the US.
The star, 20, who is in a relationship with boy band member Justin Timberlake, has famously said that she would remain a virgin in real life until she marries.