The world's top smartphone maker said it had entered into a deal to buy the US app maker, which allows people to monitor and control their home appliances via mobile devices.
"With Samsung's resources and support, SmartThings will be able to expand its platform and become available for even more partners and devices," Samsung said in a statement.
It gave no details of the value of the deal.
SmartThings will continue to operate independently under its founder and CEO Alex Hawkinson and will become part of Samsung's Open Innovation Centre, the statement said.
The centre is responsible for developing Samsung's new software and services.
"We are committed to maintaining SmartThings' open platform, fostering more explosive growth, and becoming its newest strategic partner," the centre's head, David Eun, said in the statement.
SmartThings, founded in 2012, has built an open platform that supports about 1,000 devices.
Samsung produces electronic products including handsets, memory chips, TVs and other home appliances like washing machines and refrigerators.
But the company earns more than a half of its sales and profits from its mobile business, which is faced with increasing competition in an increasingly saturated market.
Samsung last month reported a 20-percent drop in its net profit for the second quarter with analysts predicting a bleak future for its key mobile unit.
The firm has ramped up efforts to promote Internet-enabled wearable devices like smartwatches, in a move towards the market for the Internet of Things, in which household appliances and electronic devices are connected through the network.