The gaffe was picked up by a number of viewers, among them Sanjeev Bhaskar, who suggested the broadcaster had "misunderstood diversity issues".
ITV News blamed the mistake on "an error in the production process".
Sir Lenny said he was "very thankful" to receive a knighthood from the Queen for services to drama and charity.
The Comic Relief co-founder has often spoken out on the subject of diversity in the media, a topic he was again asked to comment about on Friday.
"We've made progress as far as on-screen representation is concerned," said the 57-year-old following the investiture ceremony at Windsor Castle.
"But there's a lot of work to be done in the furthering of diversity behind the camera."
"ITV News apologises for the error broadcast in the lunchtime news package today regarding Sir Lenny Henry's knighthood at the palace," said an ITV News spokesperson.
"This was the result of an error in the production process in a piece intended to celebrate Sir Lenny's significant achievements in British entertainment."
BBC News has contacted Ainsley Harriott for comment.

Clydesdale Bank's Scottish £5 note was the first fully polymer banknote to enter circulation in Great Britain.
The International Bank Note Society has nominated the fivers, made from a polymer substrate, for the award alongside banknotes from countries including New Zealand and China.
They are the only UK note on the shortlist.
Clydesdale chief executive David Duffy said: "We are proud that our polymer £5 note has been nominated.
"We take our responsibility as an issuer of banknotes seriously."
Two million of the £5 notes are currently in circulation.
The bank introduces around £400m of new notes every year.
A new polymer £10 note, featuring Robert Burns, will start to be made later in 2016 and is expected to enter circulation in 2017.
More than 20 countries around the world have adopted polymer notes.
The Bank of England is to begin issuing them later this year.
In 1999, Northern Bank of Northern Ireland issued a polymer £5 commemorative note celebrating the year 2000.

In the year to October 2015, 135 transgender hate offences were recorded, compared with 108 last year.
The Met said the rise was partly explained by more people reporting such crimes, and urged any victims of transphobia to come forward.
One London-based LGBT charity said the real number of offences was higher.
The Met figures also show that homophobic crime has risen by 21% - from 1,421 offences in 2014 to 1,724 in 2015.
Melanie Stray, from LGBT charity Galop, told the BBC this type of crime was still being underreported.
She said: "The figures that are being reported in London in a year, we have clients that experience that themselves in a year.
"I think it's the everyday stuff that happens - people couldn't report all of it because they'd spend their lives speaking to the police."
Commander Mark Chishty from the Met stressed the need for victims to contact the police in every instance, saying: "However mundane you think it is, it's very serious to us.
"It's important that we tackle this so we start curbing this type of behaviour within society - it's not tolerable, it's not part of our values and we want to deal with it."
The Met recently formed a special hate crime senior partnership group between the police and community representatives, working alongside its dedicated LGBT Liaison Officers.

Third Energy submitted an application to extract shale gas at a site near Kirby Misperton in Ryedale in May 2015.
The authority said a report on the application had not yet been finalised but it had received more than 4,000 representations about the proposals.
Third Energy said it aimed to "minimise disruption to the local community".
Rasik Valand, chief executive of the company, said: "The hydraulic fracturing and testing is a key step towards determining the viability of producing gas from this hybrid sandstone and shale formation in North Yorkshire."
The county council's decision on the planning application had originally been expected last November but was delayed after the authority requested more information from Third Energy.
The council said it recognised there would be considerable public interest in the decision and was making arrangements to ensure the meeting, at County Hall in Northallerton, was managed "safely and effectively".
Environmental permits have already been granted to Third Energy by the Environment Agency.
ITV has apologised for showing a news item about Sir Lenny Henry receiving a knighthood that briefly featured footage of TV cook Ainsley Harriott.
[NEXT_CONCEPT]
Britain's first fully polymer £5 note is in the running for the International Banknote of the Year award.
[NEXT_CONCEPT]
A 25% increase in hate crimes against transgender people has been recorded in London this year, according to figures released by the Met Police.
[NEXT_CONCEPT]
A decision on whether to allow fracking at a site in North Yorkshire will be taken on 20 May, the county council has said.