Ferrer will seek his third straight championship in Auckland when he faces Philipp Kohlschreiber on Saturday.
The top-seeded Ferrer won this tournament in 2007 in addition to each of the last two years. He needed only 49 minutes to breeze past Monfils.
Ferrer will go into next week's Australian Open as the No. 4 seed and will be trying to extend the run of outstanding play he demonstrated in 2012. He led the tour in victories last year with seven and reached at least the quarterfinals in all four major championships.
Kohlschreiber, the second seed, outlasted Sam Querrey in the other semifinal 6-4, 7-6 (7-2).
Ferrer has won six of his nine meetings with Kohlschreiber, one of those victories coming in the quarterfinals of this tournament last year.