The Scot, 29, asserted his dominance in the first set against Frenchman Tsonga in his 78th singles match of the year.
But he faced a revived Tsonga in the second, needing a tie-break to win it.
The Briton will replace Novak Djokovic as number one by winning next week's Paris Masters, provided Djokovic does not reach the final.
Three times a Grand Slam winner and twice Olympic champion, Murray has never been top of the world rankings.
His win in Vienna win is his third consecutive title after recent successes in Beijing and Shanghai and he has lost only three times since the French Open in June.
For the first set and a half it was Murray who controlled the match but Tsonga, who had beaten Murray only twice in their previous 15 meetings, came alive and produced an aggressive display to take the second set to a tie-break.
Tsonga continued to attack at the net but Murray's fifth ace of the match ensured a career-best seventh title of the season.
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