Motherhood has definitely done wonders for Beyonce!

The "Bootylicious" mom stepped out in New York for a second night in a row ... to catch Jay-Z's benefit concert for United Way and his Shawn Carter Scholarship Foundation at Carnegie Hall.

Just one month after giving birth to daughter Blue Ivy, Beyonce slipped into a blue form-fitting Monique Lhuillier sparkly number ... paired with a Chanel purse, Gucci shoes and Lorraine Schwartz bling.

Yesterday, Jay-Z's 30-year-old wifey stunned in red.

Can't wait to see what she chooses to wear for her next night out!