World Rally Championship leader Ogier faced the prospect of tackling the event without his regular partner after Ingrassia required surgery on collarbone damage from a cycling crash.
Ingrassia sat out recent Volkswagen tests, but was passed fit for Finland after a test drive and medical examination this weekend.
VW boss Jost Capito said the team had been keen that Ingrassia prioritised his health.
"The whole team is very happy that Julien is back to full health and can start racing again," said Capito.
"Our main priority is always the well-being of our drivers - we never want to take any risks.
"In the worst-case scenario, it would have been better that Julien sits out one race than risk being out for a long time. You can only start a world championship rally if you are in good health."
Thierry Neuville's sometime co-driver Nicolas Klinger had been lined up to stand in for Ingrassia if required, and worked with Ogier during testing this month.
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