The couple, which began dating in June 2015, sealed the deal on a four-bedroom, six-bathroom mansion in Brentwood, California, reported TMZ.
The property, designed by famed architect Gerard Colcord, had been on the market for USD 12.5 million, but Kerr, 33, and Snapchat co-founder Spiegel reportedly snagged the pad at a slight discount, paying USD 12 million instead.
The main house also boasts a pool and a home gym.
The news emerges three months after Kerr and her 25-year-old boyfriend made their red carpet debut together at a pre-Grammy Awards party in February.