The Spanish full-back secured a sixth straight win for Gus Poyet's men to nudge them closer to promotion when he tucked in Craig Noone's cross at the far post after 64 minutes.
County, now beaten in five of their last six games, put up a spirited display but Brighton keeper Casper Ankergren was rarely tested as the Seagulls pulled off their ninth win in a row at home.
Striker Chris Wood wasted two good chances for Brighton inside the first five minutes. The New Zealander put the ball in the side-netting following a cross by Calderon before heading an Elliott Bennett free-kick over from six yards.
Seagulls top scorer Glenn Murray was also off target when directing a header over following a Gary Dicker corner, before County keeper Stuart Nelson tipped a dipping 25-yard drive from Bennett over.
Albion substitute Francisco Sandaza forced Nelson to make a good late save and Brighton comfortably held on with Ankergren easily keeping out a late effort from Alan Gow.