Telecoms firm Total registered the name YourView for one of its online portal products in 2006.
A judge ruled that YouView was "confusingly similar" to YourView.
Total said it would now apply for an injunction to prevent further use of the YouView brand. YouView said it planned to appeal.
In a statement, YouView said: "We maintain there is no confusion between our consumer-facing TV service, YouView, and the business-to-business billing platform, Yourview, provided by Total Ltd."
But Total's lawyer Paul Gordon said: "Total's rights were plainly infringed and it had to stand firm against a much larger and better-funded opponent.
"The judgment of Mr Justice Sales has vindicated Total's position. It shows that the courts of this country will protect parties against businesses such as YouView who infringe intellectual property rights.
"YouView were made well aware of Total's rights before they launched the service under the infringing name yet they chose to launch it under that name regardless."
Total added it would now seek an injunction to "prevent any further use of the name YouView, together with financial payment and legal costs".
YouView is an internet TV service launched in July 2012 as a joint venture between BBC, ITV, Channel 4 and Channel 5 - as well as telecoms companies BT, TalkTalk and Arqiva.
Lord Sugar was the company's non-executive chairman until he stood down in March 2013.
The company says it has more than one million users across the UK, and eventually aims to increase that number to 10 million.
The service's working title had been Project Canvas, changing to YouView in September 2010.
The name caused early concern - intellectual property lawyers warned that it could be confused with Google's video sharing site YouTube.
Legal action from Total to sue YouView was launched in November 2012.
On Monday, Mr Justice Sales ruled that the convergence of the telecoms and TV industry - as demonstrated by YouView's backers - risked a "strong likelihood of confusion on the part of the public".
Source: BBC News
