The 47-year-old actress - who has six-year-old daughter Nahla with her ex-boyfriend - will have the make the hefty payments until their child turns 19 or graduates from high school, whichever happens first.
A judge in Los Angeles also awarded the Canadian model, 38, $115,000 in back payments during a hearing on May 30.
The former couple share equal custody of their daughter, according to court documents, obtained by PEOPLE.com.
The duo split in April 2010 after two years of dating and reached an initial custody agreement in late 2012 after Gabriel got into a violent altercation with Halle's now-husband Olivier Martinez, with whom she has eight-month-old son Maceo.
The French actor and Gabriel reached a mutual decision not to pursue criminal charges for Nahla's sake after Gabriel originally filed for a restraining order against Olivier, claiming he had threatened to kill him during the dispute in November 2012.
The row stemmed from Gabriel blocking Halle from moving to France with their daughter to escape attention from the paparazzi.
The 'X-Men: Days of Future Past' star recently admitted that becoming a mother has completely changed her attitude to her career.
She said: "Being a mom - that started when I had my daughter six years ago - you do start to bring different levels to your performances because being a mom is so life-changing and transforming when you have that right of passage and so it would be very hard for me not to bring that to every single thing that I do and I love that."