The 73-year-old veteran politician has led France's centre-right Democratic Movement since he founded it in 2007 and is a longtime ally of Macron. He will now be expected to form a new government in the coming weeks.
Speaking shortly after his appointment, Bayrou warned of "a long road" ahead in overcoming France's political impasse, but added that he was determined to bring about unity.
"Everyone understands the difficulty of the task. Everyone says to themselves that there is a path to find that brings together the people instead of dividing them," he told journalists, according to Reuters.