Nest offers apps for iPhone and Android that allows people to adjust their thermostat and check in on their smoke detector from their phone.
Nest co-founder Tony Fadell said the company would be run fairly autonomously.
"Google will help us fully realize our vision of the conscious home and allow us to change the world faster than we ever could if we continued to go it alone,” he said in a statement.
“We've had great momentum, but this is a rocket ship."
Nest launched in 2011 with a controllable thermostat and launched its second product, the Protect smoke and CO2 detector, in 2013.
Google said it will give the U.S.-based firm global reach.
The deal is expected to close in the next few months.