On the back of three successive defeats, the Foxes emerged from Palace with a vital three points, which were enough to propel them up to sixth in the league standings.
Annabel Blanchard opened the scoring with a smart finish inside the area for Leicester and, while Amber Stobbs levelled for the Eagles, the visitors quickly reasserted their dominance in Bromley.
Ella Rutherford's breakaway goal made it 2-1 on 57 minutes before Paige Bailey-Gayle pounced to convert after Charlie Devlin's effort cannoned back off the bar to wrap up the points.
It means City approach Sunday's FA Women's Cup Fourth Round tie at Burnley (1pm kick-off) with confidence flowing, while Leicester welcome Lewes to Farley Way in the league seven days later.
Discussing that tie at Burnley recently, Leicester City Women manager Jonathan Morgan said: “[We're] excited to be playing in such a fabulous competition.
"Burnley are flying high in the FA women’s National Northern League, sitting in second place. They are sure to be a tough test and something we are already looking forward to come 26 January.”
The details...
City: Lambourne, Johnson, Morgan (c), Cataldo (James 71'), Devlin, Blanchard, Paul (Smith 75'), Thomas, Bailey-Gayle, Rutherford, Plumptre
Subs not used: Field, Everett, Brown, Atkinson, Lawrence
Goals: Blanchard 15', Rutherford 57', Bailey-Gayle 61'
All times GMT.