After four months of twisting in the wind, Brian Williams can finally get back to work at NBC, but not without a humbling blow. Mr. Williams’s return includes a demotion, a lower salary and an apology tour that began on Thursday with NBC News staff members in New York and Washington, and will continue on national television with an interview on the “Today” show on Friday.

The broadcaster announced on Thursday that Mr. Williams, 56, would not return as the anchor of “NBC Nightly News,” but as an anchor of breaking news and special reports at the cable network MSNBC. He starts in mid-August.

Lester Holt, 56, an NBC veteran who has been filling in for Mr. Williams, will become the permanent anchor of “Nightly News.” He is the first African-American to serve as the solo anchor of a weekday evening newscast.

Mr. Williams will earn less money in his new role than at his previous job at “Nightly News,” according to two NBC executives with knowledge of the agreement, who spoke on condition of anonymity. One person characterized his pay as “substantially” less, but would not be more specific. Under a contract Mr. Williams signed in December, he was reported to be making at least $10 million a year over five years.