World Wrestling Entertainment is moving one of its weekly TV shows to cable from broadcast.

The company said Tuesday that “WWE Smackdown,” a fixture of Friday nights for millions of viewers, would be shown on the SyFy cable channel starting next fall after MyNetworkTV opted out of its contract for the show.

The announcement came a day after Conan O’Brien, the former NBC comedian, said he would join the TBS cable channel later this year, mirroring the gradual move away from broadcast by viewers and stars. “Cable is where it’s at right now,” Donna Goldsmith, the chief operating officer for the WWE, said Tuesday.

With the move to SyFy, both “Smackdown” and “WWE Raw,” the company’s biggest franchise, will be shown on cable channels owned by NBC Universal, and the only content remaining on broadcast television will be occasional specials on NBC. “WWE Raw” draws 4 million to 5 million viewers a week to the USA channel.

“Smackdown” currently averages 3.5 million viewers, representing the most-watched hours for MyNetworkTV, a little-known service owned by the News Corporation that provides programs to local TV stations.

SyFy’s president, Dave Howe, said he expected “Smackdown” to bring a “new, younger demographic to our brand.”

The channel, long identified with science fiction programming, changed its name from Sci Fi last year. It has redefined itself, rather successfully, as a broad entertainment network.

SyFy already broadcasts a weekly wrestling show, “NXT,” on Tuesday nights, and Howe characterized “Smackdown” as an upgrade. When “Smackdown” comes aboard in November, SyFy will shift some of its scripted programs from Fridays to Tuesdays. The WWE said that it was shopping “NXT” to other channels.

SyFy determined that it could not afford “Smackdown” when it considered bidding for the franchise three years ago. Although it is more expensive now, “we have an ambitious and aggressive growth strategy,” Howe said.

Goldsmith said both broadcast and cable entities had sought to license “Smackdown.” She said she did not anticipate “Smackdown” losing viewers by moving to cable because SyFy is a fully distributed channel, almost equivalent to a broadcast network. (SyFy is available in more than 95 million homes, NBC Universal says.)

Vincent McMahon, the chief executive of WWE, said last winter that he hoped to establish a WWE-branded cable channel in 2011. The WWE has held informal discussions with NBC Universal about such a channel.