Sinclair and Nexstar, the two large local TV owners that dropped “Jimmy Kimmel Live!” after the late-night comedian’s remarks about the man accused of assassinating Charlie Kirk, are resuming the program after negotiations with ABC, ending a highly unusual boycott that became a flashpoint for free speech in the United States.

The companies, which own scores of TV stations across the United States, had been pre-empting the show since its return on Tuesday, blacking out the program for millions of Americans. Both announced their decision in statements on Friday.

“Our objective throughout this process has been to ensure that programming remains accurate and engaging for the widest possible audience,” Sinclair said in a statement. “We take seriously our responsibility as local broadcasters to provide programming that serves the interests of our communities, while also honoring our obligations to air national network programming.”

The face-off with Disney began last week, days after a monologue from Mr. Kimmel that led many conservatives, including the chairman of the Federal Communications Commission, to argue that he had mischaracterized the political beliefs of Mr. Kirk’s shooter. ABC initially suspended his show indefinitely. He returned on Tuesday, setting off a fierce debate over First Amendment freedoms.

Sinclair and Nexstar refused to air his shows upon Mr. Kimmel’s return, leading to a tug of war between them on one side and Disney, ABC’s parent company, on the other. The standoff laid bare the inner workings of broadcast television, which relies on a sprawling network of local stations to deliver National Football League games, top-of-the-hour weather updates and late-night comedy to millions of Americans.

The announcements from Sinclair and Nexstar came within hours of one another. Sinclair, which went first, said in a statement that it had been in discussions with Disney about instituting a network-wide ombudsman — akin to a referee for complaints about content — but that Disney had “not yet adopted these measures.” Nexstar, which announced its decision late Friday afternoon, also said that it had “constructive” conversations with Disney, adding that it was committed to “broadcasting content that is in the best interest of the communities we serve.”

Both Nexstar and Sinclair said in their statements that they had reached the decision to pre-empt Mr. Kimmel’s show independently of federal regulators.

A spokesman for Disney declined to comment.

The decision is a striking about-face for Nexstar and Sinclair. Sinclair said last week that it would not bring back Mr. Kimmel’s show unless he apologized to Mr. Kirk’s family and made a contribution to Turning Point USA, the conservative organization Mr. Kirk founded.

It was not immediately clear what led to the change. But Sinclair owns stations in progressive strongholds, including Seattle and Portland, Ore., where viewers in droves complained about the decision on social media. In its statement, Sinclair said that it had “received thoughtful feedback from viewers, advertisers, and community leaders representing a wide range of perspectives.”

There were also financial considerations at play. Mr. Kimmel’s return to the airwaves delivered a ratings bonanza for ABC and the stations that aired the show, translating to an uptick in advertising. But during the boycott, Sinclair and Nexstar have not been able to generate ad revenue from the program.

The groups that control these local stations often have little direct interaction with viewers, who mostly know local stations by their alphabet soup call-signs and local newscasts.

For many viewers, that changed last week. Nexstar and Sinclair’s decision to pre-empt Mr. Kimmel threw a spotlight on the vast reach and influence of local station groups, which have the clout to black out shows in major metropolitan areas across the United States. Those groups own scores of stations, the result of mergers that have consolidated control of local TV in the hands of a few powerful companies.

Nexstar has a major deal pending before the Trump administration, a $6.2 billion pact to acquire the local TV colossus Tegna. To complete that merger, Nexstar would need to secure permission from the F.C.C., and it would require that agency to relax rules that limit the national reach of local TV companies.

Both actions fall within the purview of Brendan Carr, the chairman of the F.C.C., who has applauded the stations’ owners for taking matters into their own hands.

The standoff between Disney and the local TV companies has come at a pivotal time for the industry. Next week, the F.C.C. is meeting to review major rules that could reshape the television landscape, including a provision that limits a single entity from owning more than two television stations in the same local market. Mr. Carr has also expressed skepticism of a rule that prevents TV station groups from reaching more than 39 percent of Americans, a move that would probably kick off a flurry of deals among broadcast TV owners.

F.C.C. rules give local stations the right to reject programs that they believe their viewers may find unsuitable — though that provision is generally used sparingly, rather than as part of a sustained political boycott. While agreements between networks and local stations usually limit the number of times that an affiliate can pre-empt a particular program, those terms have rarely been applied to an ongoing pre-emption for political purposes.