The "Secrets and Lies" actor, 41, proposed to her girlfriend on Christmas, reported Us magazine.
The couple celebrated their engagement over lunch at Seaspice in Miami on December 27.
Phillippe and Slagter, a 24-year-old law school student, have been dating for four years.
The happy couple are expected to celebrate the new year at the Five Star New Year's Eve bash on Watson Island in Miami.
Phillippe was previously married to Reese Witherspoon from 1999 to 2007. Together they share kids Ava, 16, and Deacon, 12. The actor is also father to daughter Kai, four, with ex-girlfriend Alexis Knapp, whom he dated in 2010.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →*Subscribe to Business Standard digital and get complimentary access to The New York Times
Smart Quarterly
₹900
3 Months
₹300/Month
SAVE 25%
Smart Essential
₹2,700
1 Year
₹225/Month
SAVE 46%
*Complimentary New York Times access for the 2nd year will be given after 12 months
Super Saver
₹3,900
2 Years
₹162/Month
Subscribe
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors
Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share
Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor
Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements
Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
SAVE 25%