"I just love this course. It is an old-fashioned course where accuracy off the tee counts. You have to control the ball here," said Jimenez who began the day two shots behind overnight leader Manley.
After the final round, all three players finished on 12-under 268.
Meesawat produced a nerveless display of top-class putting to card a final-round 5-under 65 that included two eagles on the 3rd and 13th holes, which pushed him into the lead for most of the last day.
The Thai player was playing ahead of Jimenez and Manley, and took the clubhouse lead to watch nervously as first Jimenez and then Manley caught up with him.
"I was very pleased with my round," Meesawat said. "But I had a few chances to collect a couple more birdies. Unfortunately they fell short and in the playoff I had a bad approach shot."
Jimenez knocked in a birdie on the 17th and then Manley needed a last-gasp chip from the edge of the green to hole a birdie on the 18th to force the three-way playoff.
Jimenez's experience held him in good stead in the playoff as the Spaniard held his nerve to drive his approach shot at the tricky par-4 410-yard 18 on to the green. Manley had sliced his shot on to a corporate box roof while Meesawat's approach fell just short of the green.
Both missed their birdie putts but Jimenez made no mistake as he coolly knocked in the winning shot that earned him the victory.
Robert-Jan Derksen of the Netherlands finished fourth after carding an 11-under 269, while three shots further behind on 8-under 272 and tied-fifth were Spaniards Javier Colomo and Jose Manuel Lara and Angelo Que of the Philippines.
Jimenez's fourth Hong Kong Open title matched the record held by Taiwan's Hsieh Yong Yo, who won the tournament in 1963, '64, '75 and '78.
"I turn 50 next month but I'm still fit. I stretch every morning, you have to do this to keep up with the younger lot," added Jimenez.
