He will join the programme on Tuesday, 6 April, after the Easter weekend, as the permanent replacement for Alastair Stewart who left last year to present the ITV early evening news.
MacIntyre currently presents a Sunday night show on Radio 5 Live but rose to fame with hard-hitting investigations for the BBC and ITV, which resulted in him winning two Royal Television Society awards, among other accolades.
He is perhaps best known for his MacIntyre Investigates programmes for the BBC; however he has also fronted a series on Channel 5 called MacIntyre's Underworld: Gangster, along with other shows for the broadcaster and Sky. MacIntyre said: "I'm delighted to join ITV London Tonight.
"Having a background like mine: Irish, American and more, the thing I am more than anything is a Londoner - and the prospect of being part of the London Tonight team is very exciting for me.
"I'm looking forward to being part of a talented and ambitious editorial team that gets under the skin of the stories that really matter to London."
Oliver Luft writes for Press Gazette.