The benchmark Nikkei 225 index was up 0.16 percent or 34.71 points at 21,568.19 in early trade, while the broader Topix Index was up 0.19 percent or 3.02 points at 1,574.34.

"Japanese shares are seen rising in morning trade following rise in the US market, with Chair Powell's dovish comments having a positive impact on the market," Okasan Online Securities said in a commentary.

But investors were also cautious ahead of corporate earnings season later this month, analysts said.

The dollar fetched 108.16 yen in early Asian trade, against 108.46 yen in New York.

In the first of two days of congressional testimony, Powell said many central bankers believed the case for lower rates "had strengthened" as myriad trade conflicts cloud the growth outlook.

Since the June meeting, when Powell's remarks were interpreted as signalling a possible cut, "it appears that uncertainties around trade tension and concerns about the strength of the global economy continue to weigh on the US economic outlook," he said.

The remarks conformed to broad investor expectations about what Powell would say and appeared to quash speculation that last week's strong US jobs report would prevent a rate cut later this month.

In Tokyo, Nintendo was up 2.80 percent at 41,120 yen after it announced a release of a portable game console Nintendo Switch Lite.

Chip-making equipment manufacturer Tokyo Electron was up 1.10 percent at 16,585 yen, while Takeda Pharmaceutical was up 1.35 percent at 3,914 yen.

On Wall Street, the Dow ended up 0.3 percent at 26,860.20.