He will be the part-time co-host of a weekday talk show that debuts in April. Starting this month, he will also periodically provide analysis to NBC Sports Radio shows and affiliated stations.
Valentine was fired in October after just one season in Boston, when the Red Sox went 69-93.
He managed the Texas Rangers from 1985-92 and the Mets from 1996-02, leading New York to the 2000 World Series. After managing in Japan, he joined ESPN as an analyst. Valentine worked in the "Sunday Night Baseball" booth in 2011.
NBC Sports Group and Dial Global launched NBC Sports Radio in September.