“The stance of monetary policy remains accommodative, thereby supporting strong labor market conditions and a sustained return to 2 percent inflation,” the Fed said in the postmeeting statement.

The announcement made little impression on financial markets because it left the Fed’s plans unchanged. The Standard & Poor’s 500-stock index rose 0.05 percent on the day to close at 2,823.21. The yield on the benchmark 10-year Treasury, which has climbed over the last few months on market expectations of stronger growth and inflation, closed at 2.7 percent, down 0.02 points on the day.

Much of the economic strengthening happened under Ms. Yellen’s leadership, a period during which the Fed extended the economic stimulus campaign it began after the 2008 financial crisis. While critics warned that the Fed had exhausted its ability to improve economic conditions, and would instead unleash inflation, Ms. Yellen convinced her fellow Fed officials that the economy had room to grow, and events proved her right.

On Wednesday, some Fed employees wore shirts or jackets with the collars turned up, or popped, in a tribute to Ms. Yellen, who favored that look in public appearances.

Mr. Powell, a Republican with a background in investment banking, consistently voted in favor of Ms. Yellen’s policies as a member of the Fed’s board, and said during the confirmation process that he intends to continue the gradual unwinding of the stimulus campaign.

The next meeting of the policymaking committee is scheduled for March 20 and 21. If the Fed raises rates, it would be the sixth consecutive quarterly tightening of monetary policy.

“For a while now, the Fed has been very predictable in the face of a pretty benign environment,” said Luke Bartholomew, an investment strategist at Aberdeen Standard Investments.