The wedding of Princess Eugenie and Jack Brooksbank was watched by an average of three million people, giving ITV its best ratings for the time slot since William and Kate's 2011 marriage.
The extended episode of This Morning, from 09:25 BST to 12:30, had some two million extra viewers and a 46% share of the audience, up from its usual 19%.
At its peak, 3.9 million viewers tuned in to watch the wedding, held at St George's Chapel in Windsor on Friday.
The figures do not include catch-up TV.
BBC One did not air the wedding on Friday, although part of it was covered on BBC Two's Victoria Derbyshire programme.
ITV said the average ratings for Friday's coverage - presented by Eamonn Holmes and Ruth Langsford - were more than three times the typical ratings for that time.
On average in 2018, 856,000 viewers tuned in to The Jeremy Kyle Show and This Morning in the same weekday slot.
The overnight viewing figures include those watching live and also ITV+1, but consolidated figures -which include those who recorded the broadcast or watched on catch-up services - will not be released for seven days.
ITV said the three-hour wedding special helped it win the time slot for the first time since November, and it was the channel's biggest audience at that time since the wedding of the Duke and Duchess of Cambridge in 2011.
But when the consolidated figures are in, they are unlikely to reach the heights of the wedding of the Duke and Duchess of Sussex in May, which was watched by a combined 11.5 million people.
That was comprised of 8.9 million people on BBC One and 2.6 million on ITV.