Time Warner Cable, one of the country’s biggest cable operators, has agreed to carry Al Jazeera America, giving the Qatar-owned broadcaster exposure to millions more households as it seeks to build an audience in the United States.

The contract, to be announced on Thursday, is vital for Al Jazeera because Time Warner Cable supplies television to millions of households in New York and Los Angeles, two essential markets. Al Jazeera America will be added to the channel lineups in those markets this year, and in Time Warner Cable’s other markets by March.

The distribution deal is the first Al Jazeera America has made since its debut two months ago, replacing Current TV. Ehab Al Shihabi, Al Jazeera America’s interim chief executive, estimated that once the deal was fully in effect, the channel would be available in about 54 million of the 100 million American homes that subscribe to satellite and cable television, up from about 44 million homes now.

Mr. Al Shihabi said Al Jazeera, which features American and international news, was in “active negotiations” with other cable and satellite distributors. He said Time Warner Cable’s decision was evidence that “we are providing fact-based, in-depth, independent news.”