Ranked outside the top-200, Tsonga returned to Montpellier to conquer the 17th ATP title and the first since Antwerp in 2017, defeating the 7th seed Pierre-Hugues Herbert 6-4, 6-2 in an hour and 13 minutes to become the seventh French victor of this event in nine years.
The former world number five saw his 2018 season wrecked by injury, but he has found form in Montpellier this week and will now face compatriot Pierre-Hugues Herbert in Sunday's decider.
The 27-year-old Herbert has won all four Grand Slam titles in doubles, but is chasing his first singles title on the ATP Tour after losing his two previous finals.
Tsonga then opened up a 5-1 lead and the match was beyond Herbert.
Russia's Daniil Medvedev claimed his fourth ATP Tour title with a straight-sets victory against Hungary's Marton Fucsovics in the final of the Sofia Open. It was fourth title in 13 months.
Windies put England in to bat in final Test
With Joseph and Gabriel falling soon after, the West Indies were skittled out for 154, which gave England a 123-run lead. Speaking afterwards, match referee Jeff Crowe said was satisfied the umpires dealt with the matter on the field.
Tsonga downed Moldova's Radu Albot 6-1, 6-3 in just 69 minutes, converting five of his six break-point opportunities and notching seven aces.
The two players were meeting for the first time on the ATP Tour and made it a contest to remember.
Tsonga won five break points in all as he breezed through 6-1 6-3, setting up the clash with Herbert, a 6-2 7-5 victor over 2012 champion Tomas Berdych.
Medvedev finished the job with a break to love.