According to TMZ, Simmons and Jenner have been seen going in and out of the same home frequently, and it has long been speculated they're dating.
The rental home costs $25,000 per month, according to TMZ, and it features five bedrooms, six bathrooms and a pool.
It was also noted that Jenner recently bought actor Charlie Sheen's old home in Beverly Hills, California, which suggests the rental may be a temporary living space for her.
The 21-year-old Simmons is coming off his first healthy NBA season during which he led the Sixers to the second round of the playoffs.
Simmons was also named Rookie of the Year after averaging 15.8 points, 8.2 assists and 8.1 rebounds per contest.