The bank had said in March that the economy [Gross Domestic Product - GDP] in 2023 would expand by 5.8%.
Njoroge did not provide details regarding the revised forecast.
The economy expanded by 4.8% last year, lower than the pace of expansion in 2021, weighed on by a contraction in the agriculture sector.
Njoroge, who will leave the post mid-next month after eight years, said he expected the farming sector to rebound strongly due to the base effects of last year's contraction, and adequate rainfall across the country.
Agriculture accounts for the bulk of economic output in the East African nation.
Tourism, which is another key sector, is reporting good forward bookings, the governor said, pointing to a strong performance in the months ahead.