Geist was born in Evanston, Illinois, to author, columnist, and current CBS News correspondent Bill Geist and social worker Jody Geist.

He attended Ridgewood High School in Ridgewood, New Jersey, where he was captain of the football and basketball teams. He later went on to graduate from Vanderbilt University in Nashville, Tennessee. While at Vanderbilt, he was an editor of the university’s official student newspaper, The Vanderbilt Hustler.

On May 24, 2003, Geist married his high-school sweetheart, Christina Sharkey, in Humacao, Puerto Rico. The couple has a daughter, Lucie Joy Geist (b. June 14, 2007) and a son George William Geist (July 8, 2009).

Geist is the older brother of Libby Geist, the Peabody Award-winning documentary film producer (Crazy Love, Black Magic, Ring of Fire).

Geist is the great-grandson of Herbie Lewis, who captained the Detroit Red Wings to two Stanley Cups and is in the Hockey Hall of Fame.

Geist began his career as an editor and producer for CNN Sports Illustrated and subsequently a field producer and reporter for CNN Sports, where he covered The Super Bowl, The NCAA Final Four, and The Masters.

In 2004, he became a writer and producer for I, Max, a short-lived sports commentary show hosted by Max Kellerman on Fox Sports Net. He joined MSNBC television in April 2005 as a senior producer of The Situation with Tucker Carlson.

Geist began substituting as a co-host on MSNBC's 6-9 a.m. morning time slot almost immediately after Don Imus was fired in late April, 2007. Geist was named permanent co-host of Morning Joe, along with Joe Scarborough and Mika Brzezinski in September, 2007. In late July, 2009, Geist began hosting his own 30-minute, 5:30—6 a.m. program Way Too Early with Willie Geist. The show airs from 5:30-6 a.m. (immediately before Morning Joe) on MSNBC.

In 2010, Geist has substituted for Matt Lauer as host of the Today TV program and as the show's newsreader. Geist also has co-hosted the 3rd hour and 4th hours of Today.

Hosting credits

• Way Too Early with Willie Geist (2009—present)
• Morning Joe (2007—present)
• Zeitgeist (2006—present)
• Scarborough Country (2006—2007)
• Tucker (formerly The Situation with Tucker Carlson) (2005—2008)
• I, Max, Writer/Producer (2004—2005)

In its "Best of NYC 2009" issue, The Village Voice declared Geist the "Best TV Sidekick Who Deserves His Own Show," writing, "Memo to MSNBC: Instead of "Countdown" reruns at 10 p.m., give Willie a proper talk show...you might have a contempo Dick Cavett on your hands." On December 28, 2009, Way Too Early with Willie Geist was listed by The Daily Beast as as one of "25 Ways To Get Smarter in 2010". The Daily Beast compared Geist's combination of news and humor to Jon Stewart's on the Comedy Central channel and Rachel Maddow's on the MSNBC channel, calling Way Too Early "2010's must-watch cable news show."