Asian markets have hit the bottom and will likely turn around in 2019 due to China's expansionary monetary policies to help spur economic growth, a Morgan Stanley strategist said on Thursday.

"The Chinese monetary cycle is diverging from the U.S. monetary cycle," said Jonathan Garner, Morgan Stanley's chief equity strategist for Asia and emerging markets.

Broadly, for the markets, "that's got to be positive when China is easing," Garner told CNBC on Thursday.

On Wednesday, the U.S. Federal Reserve raised its benchmark interest rate a quarter-point as markets expected. Hours later, on Thursday, the Chinese central bank left its short-term borrowing rates unchanged.

Beijing is beginning to ease monetary policy "in really quite a major way," Garner said.

Other measures taken by Beijing to boost economic activity include lowering property mortgage rates in some cities and the rollout of a policy tool — known as the targeted medium-term lending facility, that's aimed at encouraging loans to small and private firms, he noted.