Camelot took against against the Gambling Commission, which had issued the licence for the Health Lottery to operate in the UK.
Desmond's Northern & Shell business set up its own lottery last year, offering players the chance to win up to £100,000 cash prizes by buying tickets at retailers, helping to raise funds for UK health causes.
Camelot said that it was disappointed by the "legally-flawed and unfair decision by the court", and confirmed that it would take its case to the Court of Appeal.
But Desmond told BBC News that Camelot's case had been a "waste of time". He also stressed that the lottery raised £500,000 a week for good causes, and claimed that it was "not at all similar" to the National Lottery.
The Health Lottery manages and promotes lottery draws on behalf of 51 local organisations and charities, known as "society lotteries".
However, Camelot has always maintained that the Health Lottery, backed by Desmond's Channel 5 network, was actually a UK-wide lottery that rivals The National Lottery.
This would mean that it contravenes the 1993 National Lottery Act that stipulates there can only be one national scheme in Britain.
Camelot says that Desmond's scheme utilises a "loophole" in the Gabling Act 2005 that allows it to operate.
It branded the lottery as an "unlawful and a blatant example of an attempt to commercialise a society lottery on an industrial scale that cuts across both the spirit and letter of statute and regulation".
But Lord Justice Stanley Burton and Mr Justice Kenneth Parker, sitting in the High Court, dismissed the case.
They said that "the question whether multiple society lotteries should be permitted is a political question, to be determined by the Government or Parliament".
The judges refused Camelot's request for a judicial review, although the company said it will appeal the verdict.
Camelot also wants the Department for Culture, Media & Sport to step in and review the situation.
Camelot chief executive Dainne Thompson said: "It is now imperative that the Government acts to close this loophole and to ensure that the law mirrors the intention and will of Parliament that there should be only one National Lottery.
"Time is of the essence - the longer the period of political inaction, the more incentive there is for other commercial operators to establish similar mass-market lotteries that would effectively cannibalise National Lottery sales and returns to the Good Causes.
"We are therefore calling on the Government to set out immediately the process and the timetable it intends to pursue in order to discharge its ultimate responsibility for The National Lottery and the Good Causes it supports."