The 31-year-old, a silver medallist at the Sochi Winter Olympics in 2014, remains top of the tree in the parallel giant slalom standings and the overall parallel leaderboard after topping the podium in Bansko.
Galmarini bested fellow Swiss competitor Dario Caviezel and Austria's Alexander Payer to reach the semi-finals, where he then defeated Austria's Andres Prommegger, the 2016-17 overall champion.
That set up a big final showdown with Bulgaria's Radoslav Yankov and Galmarini, whose two other victories came in Rogla, Slovenia, last season and Lackenhof in his native Switzerland earlier this month, reigned supreme by 0.67 seconds to take gold.
Meanwhile, Julia Dujmovits finds herself third in the women's parallel overall standings after her first event win of the season.
The reigning Olympic champion, 30, from Austria, progressed at the expense of Italy's Nadya Ochner and Russia's Natalia Soboleva en route to the semi-finals, where she overcame Germany's Selin Joerg.
Then, in the big final, Dujmovits defeated another German - Ramona Hofmeister, who failed to finish - to claim glory.