China poured $20 billion into ship financing this year, reflecting the country’s ambition to become the world’s dominant maritime player as European banks have scaled back their investments.

That is 33% more than Chinese banks invested in 2016, according to the leasing arm of Industrial & Commercial Bank of China Ltd. It dwarfs China’s financing as recently as 2008, when its lessors lent just a few million to shipowners that built their vessels in the country’s shipyards.

ICBC’s...