Mapledurham Playing Fields, at Caversham, are run by a Reading Borough Council-controlled charity, with football, basketball and other sports played on the 11-hectare site.
But, in August this year, Reading Council granted planning permission for a two-form primary school to be built on part of the fields.
The proposals were opposed by local pressure group, MPF Action Group, whose chairman, Martin Brommell, mounted a High Court challenge.
The school development was also opposed by government agency and statutory consultee Sport England due to the loss of playing fields.
But now, after a hearing in London, Mrs Justice Lang has rejected Brommell's complaints and confirmed the planning permission.
The court heard that a planning officer who advised councillors to grant consent had pointed to the pressing need for a new primary school in the area.
The officer acknowledged that "some difficult choices" had to be made, but the new school would have "overriding public benefits".
The chosen site was "highly accessible and appropriate" to a catchment area with an "identified deficiency" in primary school places.
Mrs Justice Lang rejected claims that the officer down-played government policies designed to protect public open spaces.
Arguments that the council gave insufficient weight to the emerging local plan, or that its decision was procedurally flawed, were also rejected.
Brommell's lawyers also claimed the council "acted irrationally" in failing to consider alternative sites for a new school.
But the judge said: "There was no statutory or policy requirement, either express or implied, to consider alternative sites in this case.
"There was no obvious alternative which avoided the disadvantages of the proposed site."
Brommell's judicial review challenge to the planning permission was dismissed.
Last week, a developer failed in its High Court bid to avoid paying a £550,000 community infrastructure levy (CIL) bill after a judge dismissed its argument that the property concerned was already in residential use when the charge was issued.
Also last week, plans for a mixed-use development in west London, including a new superstore and 221 flats, were given the green light by a High Court judge, after a rival supermarket unsuccessfully tried to halt the scheme.
R on the Application of Brommell v Reading Borough Council. Case Number: CO/3744/2018