Verdasco hammered four aces and saved six of seven break point chances in the match that lasted one hour, 52 minutes.
Verdasco has won seven of 10 career meetings with Almagro.
“I am so tired I don’t know if I can talk so much,” said Verdasco, who also reached the doubles final in Casablanca.
Almagro made Verdasco work for the victory as he hit eight aces, won 72 percent of his first serve points and saved seven of nine break points.
It marked the second year in a row Almagro finished runner-up in Houston, losing last year to John Isner.
Almagro was handed a free pass into the final when the US’ Sam Querrey was cut down by a back injury in the semi-finals.
“He played a really good match today, and he’s the winner,” Almagro said of Verdasco. “It was a battle today, and he really concentrated on his serve. I had many chances and I didn’t [take them] and that’s the key of the match.”
GRAND PRIX HASSAN II
AP, CASABLANCA, Morocco
Eighth-seeded Guillermo Garcia-Lopez won his first title in nearly four years after rallying to beat fourth seed Marcel Granollers 5-7, 6-4, 6-3 in an all-Spanish final on clay at the Grand Prix Hassan II on Sunday.
The 30-year-old Garcia-Lopez’s previous title was on indoor hard courts in Bangkok in 2010 and he had lost his previous two finals — last year on clay at Bucharest and on indoor hard courts in St Petersburg, Russia.
Granollers, who was bidding for his fifth career title, dropped his serve five times and was less consistent in Casablanca, Morocco.
The 28-year-old won only 60 percent of first-serve points, compared with 76 percent for Garcia-Lopez, who won their only previous meeting in the second round of the same tournament in 2010.
Garcia-Lopez continued the recent dominance of his countrymen at the tournament, becoming the fourth Spaniard to take the title over the past six years after Tommy Robredo won it last year, Pablo Andujar in 2011 and 2012, and former French Open champion Juan Carlos Ferrero in 2009.