The Senate on Tuesday confirmed Lina Khan, a prominent critic of the country’s largest tech companies, to the Federal Trade Commission.

Legislators voted 69-28 to endorse Ms. Khan, 32, who first stood out as a critic of Amazon. The authority is investigating the trading giant and filed an antitrust lawsuit against Facebook last year.

Ms. Khan will help regulate the behavior that has been highlighted for years by critics from Amazon, Facebook, Google, and Apple. Speaking before a Senate committee in April, she said she was concerned about how tech companies could use their power to dominate new markets.

Her appointment was a victory for progressive activists who want Mr. Biden to take a tough line against big corporations. He also gave Tim Wu, a law professor who has criticized the power of tech giants, a job in the White House.

But Mr Biden still has two key positions that are charged with regulating the industry. He has not appointed the permanent chairman of the FTC, nor has he appointed anyone to lead the Justice Department’s antitrust division.