The visiting captain fired home a left-footed volley in the 48th minute following Marvin McCoy's weak defensive header for the only goal of the game.
The win ended Wycombe's six-match unbeaten run while Plymouth are now just outside the play-off zone by goal difference.
Both sides struggled in a tentative first half with Matt McClure registering the only effort on target, but the Wycombe striker saw his 35th minute header easily collected by Jake Cole.
Right-back Durrell Berry volleyed wide for Plymouth before Cole was called into action again on the stroke of half time, tipping Sam Wood's in-swinging corner onto the crossbar.
Hourihane's fifth goal of the season immediately after the break proved the telling difference as the home side lacked the quality to properly test Cole.
Reuben Reid could have doubled Argyle's lead but saw two fine strikes beaten away by Matt Ingram as Plymouth easily held on for the win.