Around 1,000 workers at the privately-owned M.K.B. Tea Estate attacked the plantation owner's bungalow on Wednesday and set it on fire in violence blamed on festering labour unrest in the tea-growing region, police said.
Mridul Bhattacharya and his wife Rita were burned to death as workers armed with home-made weapons prevented police from rescuing them, they said.
"The body of the planter was charred beyond recognition and reduced to ashes while the body of the wife was found lying in the kitchen," local police officer A. Das told AFP by telephone.
The grisly attack occurred in Assam's tea-growing Tinsukia district, some 500 kilometres (310 miles) east of the state's main city of Guwahati.
The Indian Express newspaper said the violence was sparked by orders served by Bhattacharya on 10 estate workers to vacate their quarters and the detention of three employees by police over unspecified disputes.
Plantation workers were seen on local television channels admitting to having carried out an attack.
"We all came and attacked the bungalow and set it on fire. They deserved to be killed as the planter has exploited us for a long time and tortured us for petty things," a tea estate female worker said on News Live local TV channel.
The station did not identify the woman.
Assam produces around 55 percent of India's annual tea production, which stood at 988.32 million kilograms (2,174.3 million pounds) last year, and the state is home to more than 800 tea estates.