President-elect Donald J. Trump has chosen Representative Michael Waltz of Florida to be his national security adviser, two people familiar with the decision said on Monday, turning to a former Green Beret who has taken a tough line on China to oversee foreign and national security policy in the White House.

Mr. Waltz is the second Republican member of the House to be selected by Mr. Trump for a high-level job in his next administration, after the president-elect’s choice of Representative Elise Stefanik of New York to be his ambassador to the United Nations.

Mr. Waltz, 50, has been a member of the House Armed Services, Intelligence and Foreign Affairs Committees. His wife, Julia Nesheiwat, was homeland security adviser in the first Trump administration.

Mr. Trump will take office with a full plate of foreign policy issues, including Russia’s war in Ukraine, the conflict in the Middle East and confronting an increasingly aggressive China.

The Wall Street Journal earlier reported the move.