During the first semi-final of the show's most recent series, Britain's Got Talent viewers could use a downloadable smartphone app to cast their votes on the contestants.
The votes were offered in batches of three costing £1.49, but the scheme collapsed in the very first voting period on May 6, due to a technical problem that meant some users could not cast their votes.
After a viewer contacted Ofcom to report the problem, the regulator investigated and found that just 49% of votes on the app were successfully cast by users.
ITV said that it takes its obligations on interactivity and voting "extremely seriously", particularly as the broadcaster has fallen foul of Ofcom in the past, including a £5.7m fine in relation to voting schemes in 2008.
The broadcaster said that the Britain's Got Talent app's firewall was not able to process the high volume of interactions that occurred when voting started.
This meant that "while some users were able to use votes that they had purchased, others were not and some were charged for votes that they did not receive and so could not use".
ITV attributed the problems to a "firewall mis-configuration" on the part of the voting platform provider, caused by a lack of end-to-end testing on behalf of the third party.
However, the broadcaster accepted "full responsibility" for the problems and said that after an internal investigation, it dropped in-app voting for the rest of the series.
A full refund procedure was implemented for people who had purchased unused votes, and an announcement to that effect was also broadcast during the third semi-final and published on the ITV website.
In its ruling, Ofcom gave a critical assessment of ITV's use of in-app voting for Britain's Got Talent, but ultimately decided that the action taken by ITV was sufficient to resolve the matter.
Ofcom said that voting via smartphone apps is a "relatively new concept", but said it was "concerned" that ITV's app was unable to handle the demand when voting opened.
This meant that that over half of votes could not be cast, meaning viewers "were effectively misled, albeit unintentionally".
"In this case we were of the view that the cause of the problem contained elements both of preventable design weakness and less easily anticipated patterns of demand," said Ofcom.
"We noted ITV's swift action to cancel the application and provide details of how users could obtain a refund. We also noted ITV's review of its processes to avoid a recurrence should it use a similar voting mechanism in future programming.
"In view of the Licensee's remedial measures, Ofcom considers the matter resolved and does not expect a recurrence of the problem and takes this opportunity to remind ITV of its obligations under the Code in this area and its responsibilities under its licence in relation to its communications with viewers."
Ofcom advised all broadcasters to take a "precautionary approach" to the trial and deployment of interactive voting applications for TV shows in the future.
In March, Ofcom cleared Channel 5 following a row over lost Facebook votes during the live Big Brother final last year.