A survey by Deloitte and GfK has found that a fifth of 18-24 year olds who saw a product or service on TV have went on to buy it online.
This makes it the third most powerful purchasing influence for this group, behind finding a product in store and recommendations from family or friends.
Social networking was not found to be a popular purchase driver, with Facebook scoring 3% and Twitter 2%.
The survey of 4,000 adults also found that 68% of people browse the internet at least occasionally when watching TV, while 45% of participants would shop online at the same time as watching.
Jolyon Barker, Deloitte's global lead, technology, media and telecommunications, said: “Today television appears to exert a significant influence on purchasing decisions made within the living room and in the high-street.
“Being connected means TV viewers can research, typically in the form of price comparisons and reviews, and transact - all within the space of an advertising break. All of this is very powerful to broadcaster.
“But they would need to up their game significantly in terms of monitoring the online response to their programmes and adverts, and utilising this rich data.”