Boosted by 21,000 football fans using the Rhoose-based airport for the Champions League Final, it handled 185,787 passengers in total.
The figure represents a 19% rise on June, 2016. It was also the highest monthly figure since it was acquired by the Welsh Government in March, 2013, for £52m from Spanish conglomerate Abertis.
At the time the annual passenger number had fallen below one million.
For the rolling year to the end of June, passenger numbers at the airport surpassed 1.4 million.
The highest annual passenger number achieved by the airport was 2.3 million. when under the ownership, of TBI back in 2007 – a year in which it also achieved its highest ever monthly figure with 264,656 in August.
Commercial director of Cardiff Airport, Spencer Birn, said: “The first half of 2017 has seen a step change for Wales’ national airport. We’ve welcomed new airlines and our existing airline partners are reacting to increased market demand by adding new routes and extra capacity.
With Qatar Airways launching in 2018, we’ll be working with the airline to ensure this exciting service opens up new opportunities for customers in Wales and the South West as the region’s first direct link to a major Middle East airport hub, offering connections across Africa, Asia, Australia and more.”