In a break with European tradition, ITV said in a statement that it will split the screen twice per match to show an ad as the game breaks for a scrum.
Each advertisement per half will last 20 seconds, with the left-hand side of the screen continuing to show the game with slightly-reduced sound and the right-hand broadcasting an ad with sound.
The first companies to sign up to the new format are Samsung and Virgin Atlantic, ITV said.
"We won't know either the viewing audience's reaction nor how well it was monetised" until after the tournament, Gill Hind, a television industry analyst at Enders, told AFP.
"It's certainly more intrusive than at present."
ITV is set to show 10 live matches from the annual tournament beginning Thursday, including all of England's five fixtures against France, Ireland, Italy, Scotland and Wales.
On-screen ad inserts during live matches are common practice in the United States, but not in Europe, where TV commercials are traditionally shown before and after a game, and during half-time.
European television broadcasters could meanwhile show in-game ads at this year's football World Cup in the United States, Canada and Mexico.
This is after football governing body FIFA said it would allow three-minute hydration breaks in the middle of each half, in addition to the traditional 15-minute half-time interval.