In a note posted on the newscast's public relations website, Williams says Lester Holt will be taking his place while he is gone.
"In the midst of a career spent covering and consuming news, it has become painfully apparent to me that I am presently too much a part of the news, due to my actions," writes Williams, who's also managing editor of NBC Nightly News.
"Upon my return, I will continue my career-long effort to be worthy of the trust of those who place their trust in us."
Williams apologized Wednesday for telling the story a week earlier in a Nightly News tribute to a veteran he had befriended during a 2003 reporting trip to Iraq. Before expressing his regrets on the air, Williams did so online and in an interview with the newspaper Stars & Stripes.