Newbridge Preparatory School, in Tettenhall, was named the The Sunday Times' Independent Preparatory School of the Year 2020.
It comes after a review was carried out of the national league tables, based on KS2 SATs, with inspection reports also scrutinised.
Alastair McCall, editor of the Sunday Times Schools Guide, praised the school – and its staff – highly.
Mr McCall said: "Newbridge is an educational gem, a precious find for the 160 children lucky enough to go there.
"It manages to pull off the notable feat of achieving outstanding academic results – bettered by just four schools in England across the state and independent sectors – alongside developing the wider interests of its pupils , or allowing the children to have time for a childhood, to use the words of its excellent head teacher Sarah Fisher.
"The school may have non-selective entry but by the time the girls leave at 11 they are much in demand across the best state and independent schools in the West Midlands.
"If ever the quality of education on offer here was a 'best kept secret', this award should ensure that is not the case for very much longer."
Sarah Fisher, headmistress at the school, said to be named was an "outstanding achievement" – adding it was testament to the "quality, depth and breadth" of the education offered.
Ms Fisher: "It's an outstanding achievement for any school – but for a small, non-selective school in Wolverhampton this is remarkable, we beat off competition from the top London schools.
"It's something to make the city proud."