Set-up issues with their Citroën DS3 S2000 slowed down Kubica and his co-driver Maciek Baran early on, but the pair persevered.
In the end, they were beaten to a class victory only by local specialist Jari Ketomaa, as they successfully fended off former P-WRC champion Hayden Paddon, who finished third.
The former F1 star saluted Ketomaa's vast experience of the Rally Finland.
"Ketomaa told me that he had driven on some stages more than fifteen times in the Finnish Championship," is quoted saying by Crash.net. "So it was never going to be easy to challenge him!"
Kubica's second-place has brought him back within 23 points of the WRC2 championship's lead, as both his rivals, Abdulaziz Al Kuwari and Nicolas Fuchs, failed to score any point in Finland.
As well as coming home second in class, Kubica finished ninth overall.