In a large bowl, beat the softened cream cheese until smooth and creamy.
Gradually add the sifted powdered sugar to the cream cheese, mixing on low speed until fully incorporated.
Stir in the fresh lemon juice, lemon zest, and vanilla extract, whisking until the base is light and fluffy.
In a separate chilled bowl, whip the heavy whipping cream until stiff peaks form.
Using a rubber spatula, gently fold the whipped cream into the lemon cream cheese mixture in two batches until well combined and airy.
Divide the mousse into serving glasses or bowls.
Chill in the refrigerator for at least 1 hour before serving.