"It is a tremendous victory. It is a united effort by the teammates," he said attending a function at a school here.
Hailing leadership skills of Captain Virat Kholi, who took over the reins of the team from M S Dhoni, Kumble said the Lankan win would boost his confidence further.
India clinched their first Test series victory in Sri Lanka in 22 years, recording a 117-run win in the third and final Test for a 2-1 margin earlier this month.
The last time an Indian team won a series in Sri Lanka was way back in 1993 under Mohammed Azharuddin's leadership when they sealed the series with 1-0 scoreline.