Justine is married to John Leguizamo, who is a renowned actor, stand-up comedian and producer. John Leguizamo is also a playwright, screenwriter and voice actor. Justine is Leguizamo’s second wife; his first marriage with the actress Yelba Osorio was unsuccessful. They met on the set of the movie “Carlito’s Way”, which proved to be a turning point in both their lives. Leguizamo played the role of Bennie Blanco, a Latino drug dealer who eventually causes the downfall of the title character, played by Al Pacino. Leguizamo says “What happened to me in Carlito’s Way was that I had worked with De Palma, so this is my second time with him, so…he trusted me. I did a lot of research for the part and I knew people like that growing up, I mean drug dealers, and they let me go. I started improvising like crazy and adding all this text and De Palma loved it. And so I feel like I really found myself, like what it was to be present in the moment, to be as explosive and as volatile as you can be and also as quiet...that’s how I found myself.” The confidence Leguizamo found on the silver screen seemed to carry over into his real life and he attracted the attention of the young costumer, Justine Maurer.

John and Justine dated for over five years before getting married. The couple was married to each other on July 5, 2003. Their wedding was a Catholic-Jewish ceremony as John is Catholic and Justine is Jewish.  The couple has been together fifteen years and it does not look like a divorce or any other marital quarrels are in their future, even though that often happens to others. The couple has two children together,  a son named Ryder Lee "Lucas" Leguizamo and a daughter named Allegra Sky Leguizamo. Both children were born before John and Justine were married but that does not seem to have affected their relationship in any negative way and the couple have put together a nice life.

The young family has an active social life and often gets together with John’s extended family. When Leguizamo gets together with his family “things get loud” John told Time magazine. “My wife knows that [my family members are] all very passionate and we talk about everything and there's no holds barred when we get together. We talk about everything and anything loudly.”

The couple’s daughter, Allegra Sky Leguizamo,  is also an actress, just like  her father. Allegra was born on October 23, 1999. The youngest child, a son named Ryder Lee Leguizamo, was born on December 5, 2000, he is also an actor.