The 2019 Boston Marathon will be broadcast live from Boston, Massachusetts Monday, April 15 via NBC Sports Network television network, NBC Sports Gold and locally on CBS Boston WBZ-TV. 

From the event website:

NATIONAL COVERAGE: NBC SPORTS NETWORK

• National coverage of the 123rd running of the Boston Marathon:
  • Sunday, 4:00 p.m. ET to 5:00 p.m. ET, Preview Show, Olympic Channel
  • Monday, 8:30 a.m. ET to 1:00 p.m. ET, Race Day Coverage, NBCSN and NBCSN Gold
• NBC Sports Group and the Boston Athletic Association have a multi-year agreement for NBCSN and NBC Sports app to serve as the national television and streaming destinations for the legendary Boston Marathon.
• NBC Sports Group serves sports fans 24/7 with premier live events, insightful studio shows, and compelling original programming.
• The sports media company consists of a unique array of sports assets, including NBC Sports, NBC Olympics, NBCSN (NBC Sports Network), Golf Channel, nine NBC Sports regional networks, NBC Sports Radio, and NBC Sports Digital.
• NBC Sports Group possesses an unparalleled collection of television rights agreements, partnering with some of the most prestigious sports properties in the world: the International Olympic Committee and United States Olympic Committee, the NFL, NHL, NASCAR, PGA Tour, The R&A, PGA of America, Churchill Downs, Premier League, Tour de France, French Open, Formula One, IndyCar, and many more.
• For more information, please visit www.nbcsports.com.

LOCAL COVERAGE: WBZ-TV

• Local coverage of the 123rd running of the Boston Marathon:
  • 4:30 a.m., Morning News, WBZ Channel 4
  • 7:00 a.m., Boston Marathon Pre-Race Show, WBZ Channel 4
  • 9:00 a.m., Boston Marathon Live Coverage, WBZ Channel 4
  • 4:00 p.m. to 6:30 p.m., Evening News, WBZ Channel 4
  • 8:00 p.m., Boston Marathon Replay Show, myTV38
• CBS Boston’s WBZ-TV is honored to once again be the exclusive local broadcast partner of the Boston Marathon, providing live wire-to-wire coverage of this world-class race for over 35 years.
• WBZ-TV offers a full range of Boston Marathon news, features, and athlete interviews, from the pre-dawn hours in Hopkinton to the celebration and emotion at the finish line in Copley Square…all to get viewers closer to Boston Marathon news and information as well as what the race means locally and around the world.
• Dedicated to serving the community, WBZ-TV is proud of its legacy as the exclusive broadcast partner to many of Boston’s signature events.
• For more about CBS Boston’s WBZ-TV, go to www.cbsboston.com.