Flames were reported on Monday at 7.30am on the fifth floor of a residential building for reasons not yet determined, police said.
A team of 14 fire fighters with six vehicles from Locarno put out the blaze but were unable to save the tenant.
The person’s lifeless body was found inside the apartment, police said.
Part of the apartment was completely destroyed while the rest of the home sustained smoke damage.
Forensic investigators are probing the cause of the fire, police said.
Meanwhile, Ticino police said another fire near Locarno on Monday night destroyed two farms.
No-one was inside the buildings located near Versicio in the mountains north-west of Locarno.