Kushner is a co-founder of Oscar Health, a health insurance start-up. Founded in 2012, Oscar was valued at $2.7 billion in 2016. As of 2015, the company insured over 145,000 members across four states, and has been named to CNBC's Disruptor 50, Inc. Magazine's Most Innovative Start-Ups, and MM&M Top 40 Health Care Transformers.
Kushner started dating model Karlie Kloss in 2012. The couple got engaged in July 2018, and were married on October 18, 2018.