After quarter-final opponent Jiri Vesely was forced to withdraw due to a toe injury, a rested Andujar proved far too strong for Gilles Simon.
The Spaniard prevailed 6-1 6-1 in 74 minutes, recording five breaks of serve to reach the tournament's final for a fourth time.
Andujar now has an impressive 18-2 career record in Marrakech, though he has never beaten Paire in their three previous meetings on the ATP Tour.
The Frenchman was forced to work much harder to seal his progress, rallying from a set down to see off compatriot Jo-Wilfried Tsonga 2-6 6-4 6-3.
Having fought back after losing the opening set to draw level, Paire was then 3-1 behind in the decider before reeling off five games in a row to triumph after just under two hours on court.
The 29-year-old will have the opportunity to win a second career title, his only previous success coming at the Swedish Open four years ago.