Fox News on Monday named Bill Hemmer, one of the network’s longest-serving news anchors, to replace Shepard Smith as host of the channel’s 3 p.m. weekday newscast.

With Mr. Smith at the helm, the 3 p.m. slot often stood out from the pro-Trump commentary that now dominates Fox News’s morning and evening airtime. Mr. Smith routinely took President Trump to task for his falsehoods and invective, earning the ire of the White House and, eventually, some of his own Fox News colleagues.

Mr. Smith abruptly departed in October, disillusioned by the gap between the network’s prime-time programming and the reporting from its newsroom. Since then, his show has been hosted by a rotating group of anchors and correspondents as executives mulled a replacement.

Mr. Hemmer, 55, arrived at Fox News in 2005 from CNN. For the last decade, he has co-hosted “America’s Newsroom,” a late-morning newscast, and served as Fox News’s resident “map man” — the anchor tasked with walking viewers through state-by-state returns on election night with the help of an interactive digital screen. (Mr. Hemmer nicknamed the device the “Bill-board.”)