Free tennis coaching sessions took place throughout the afternoon while there was also a barbecue and Pimms stall.
Headteacher Jonathan Carroll said it had been a ‘brilliant afternoon’.
Construction of the courts started in January.
They were created in partnership with Delgado Tennis Club and replaced existing tennis courts.
They will be used by St Piran's pupils during the day while everyone who wants to use the new facilities can do so through the tennis club on evenings, weekends and holidays.
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