Adrian Brown made the "unscheduled landing" between Bassingbourn Primary School and the village college at about 08:40 GMT on Tuesday.
Unable to reach Royston Heath because of light winds, and not wanting to "disturb sheep" in a nearby field, he chose the playground.
Primary head Sue Brown said the unexpected visitor "made their day".
Mr Brown, from Litlington in Cambridgeshire, arrived on his single-person "hopper" balloon - one that does not have a basket -  "just as the bell was ringing", Mrs Brown said.
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He said he had set off 30 minutes earlier from a field north of Bassingbourn and was aware the wind conditions were light and variable.
"Ideally we like to land close to a road or track to enable easy access for the retrieve crew to come and collect us," Mr Brown said.
"With such light winds I didn't think we would be able to reach the heath at Royston.
"The Royston Road from Litlington has the complication of power lines and sheep in the fields which I did not want to disturb."
When he landed, Mr Brown was greeted by a familiar face - his daughter, who is a pupil at Bassingbourn Village College.
"[She] came across and said hello, which was lovely," Mr Brown said.
The engineering company boss has been ballooning for 25 years.
A man landed his hot air balloon on a Cambridgeshire school playing field "to avoid sheep", he said.