By lifting the title, the Frenchman became only the third player in the professional era to win his first six tour-level finals, matching the achievement of Latvia's Ernests Gulbis and Slovakia's Martin Klizan.
The in-form Marseille champion edged a tight opening set when seventh seed Bublik fired a double fault in the 10th game as he chanced his arm and attempted a big second serve in a desperate attempt to hold.
Left-hander Humbert, who took out top seed and Australian Open runner-up Daniil Medvedev in the semi-final, showcased his superb defensive skills to earn a chance to break in the next set and pounced for a 3-1 lead when Bublik found the net.
He unleashed a monster forehand to go 5-2 up before holding his nerve two games later to save a breakpoint and close out the contest on his second championship point with a passing winner.
