Three families who challenged the government over its approach to special needs and disability (Send) funding have lost their case at the High Court.
They said there was a crisis in funding that would "blight" children's lives.
Mr Justice Lewis dismissed their claim for a judicial review, ruling there had been no unlawful discrimination.
The education department had not acted irrationally and there had been "no breach of the general duty to promote the wellbeing of children in England".
The legal action had been brought by three children with Send on behalf of others who also rely on the funding.
Nico Heugh Simone, 15, from Robertsbridge, East Sussex, Dakota Riddell, nine, from Birmingham, and Benedict McFinnigan, 14, from Scarborough, acted through their mothers.
Jenni Richards QC, who represented the families, told the court at a hearing in June there was "clear and incontrovertible evidence" of a "substantial national shortfall" in funding.
Ms Richards had argued:
- Former Chancellor Philip Hammond had acted unlawfully in setting the national budget in October 2018
- Former Education Secretary Damian Hinds had acted unlawfully when making available additional but "manifestly insufficient" Send funding in December
But government lawyers, who opposed the legal action, had argued the increase in demand had been recognised by the ministers and Mr Hinds had "made it clear" high needs would be one of his priorities ahead of the 2019 spending review.
Giving his verdict, Mr Justice Lewis said there was "no reasonable basis" for concluding the defendants had treating children and young people with special educational needs in a similar way to other children without such needs.
"Factually, the funding system provides for additional funding through the high-needs funding block," he said. "That is currently over £6bn a year."
And the government's announcement in September it would provide an additional £700m over the next year for pupils "with the most complex needs" would address the budget for Send funding for future years.
Nico's mother, Lorraine Heugh, said: "We are understandably disappointed by the ruling.
"We campaigned for months on this issue and still believe that not only our children but thousands of other children across the country are being failed by the current system.
"Although the ruling may not have found in our favour, we will not stop campaigning for change.
"We urge the government to ensure the extra money it has promised for Send pupils finds its way to them and we hope that the ongoing reviews come back with firm proposals on how to improve services.
"We are not asking for preferential treatment, we just want children to have the best education they deserve."
Dakota's mother, Mary Riddell, said: "It was an honour and a pleasure to campaign with parent carers across the UK and fight for what our children deserve.
"I will continue to fight for what I believe is right and what our children deserve.
"On behalf of the parents, I would also like to thank all those who supported us during the case.
"The stories we heard of how other children have also been affected by Send funding vindicated our decision and now make us determined to continue to push for improvements."
Anne-Marie Irwin, specialist lawyer at Irwin Mitchell law firm, which represented the families, said it had put forward strong legal arguments that "the decisions taken about Send funding were so inadequate as to make them unlawful".
"We and the families are disappointed by today's decision but thank the court for hearing the case," she said.
'Heartbreak and frustration'
The case was supported by campaign network Send Action, as well as charities Mencap and the National Deaf Childrens' Society (NDCS).
Responding to the verdict, Send Action said: "The odds were stacked against us."
Jo Campion, from NDCS, said: "This judgement in no way alters the fact that hundreds of thousands of disabled children have seen their support slashed, their specialist teachers cut back and their vital technology withheld.
"I've seen first-hand the heartbreak, stress and immense frustration that has become a daily reality for so many families.
"The government's pledge of an extra £700m could make real progress towards alleviating the crisis ravaging the Send system but until the cheques are signed and the money arrives on the front line, disabled children across the country will continue be starved of support every single day."
A Department for Education spokesman said: "No child should be held back from reaching their potential, which is why we recently announced major new high-needs funding worth well over £700m in 2020-21.
"We have also launched a review of the system to see how it can make further improvements to make sure every child gets the education that is right for them."
The High Court has previously rejected cases brought by families of children with special educational needs against Hackney and Surrey councils.