The company was founded in 2001 and develops wearable wireless vital signs-monitoring devices for use by hospital patients and outpatients.
It has been bought by New York-based UltraLinq Healthcare.
UltraLinq said the purchase would help its strategy of developing a cost-effective digital health platform focused on cardiovascular conditions.
Intelesens currently employs a team of 39 who will remain at its site at Belfast Harbour, where the company manufactures a range of electrodes and devices.
Aidan Langan, CEO of Intelesens said the deal represented a "tremendous opportunity" for the company, as well as for the MedTech sector in Northern Ireland more generally.
Intelesens' single largest shareholder was Enterprise Equity.
The company began life as a spin-out from Ulster University.
Intelesens, a Belfast-based medical technology firm, has been bought by a US company for an undisclosed sum.