"The Fed is certainly not crazy in terms of what it's doing," Yellen said at the World Knowledge Forum in Seoul, South Korea, the Journal reported Friday.
"Removing monetary policy accommodation is a thoroughly sensible strategy. It's been well communicated," Yellen added. Yellen led the Fed for four years.
Yellen said she has confidence in Powell.
Trump continued his attack on the Fed this week, saying Powell is making a mistake by being too stringent with monetary policy. He blamed the Fed for causing a massive drop in stocks this week that took the Dow Jones Industrial Average down nearly 1,400 points on Wednesday and Thursday.
"It's a correction that I think is caused by the Fed and interest rates," Trump said from the Oval Office on Thursday. "The dollar is very strong, very powerful – and it causes difficulty doing business."
On Wednesday, Trump said: "I think the Fed is making a mistake. They are so tight. I think the Fed has gone crazy."
The Fed has hiked its benchmark interest rates three times this year, with another rate hike expected before the end of 2018 and three more likely in 2019. Despite Trump's open criticism, Yellen believes the Fed will continue with its economic strategy
Read the full story in The Wall Street Journal here.