The company, which is being acquired by market leader Comcast Corp <CMCSA.O> for $45.3 billion, lost a net 152,000 customers in the April-June quarter.
Comcast reported higher quarterly revenue and income last week as more people signed up for high-speed internet and fewer customers dropped their cable subscriptions.
As of Sept. 30, Time Warner Cable had 10.8 million household video subscribers, down from 11.4 million a year earlier.
The company, which gets more than 80 percent of its total revenue from households, also reported lower-than-expected sign-ups for its residential voice and high-speed data services.
Net income attributable to common shareholders fell to $499 million, or $1.76 per share, in the quarter, from $532 million, or $1.84 per share, a year earlier.