The firm topped the regulator's list of customer dissatisfaction throughout 2011, despite reducing its volume of complaints during the last six months.
Ofcom also revealed that 3 attracted more complaints than any other mobile network provider in 2011. Charge disputes and customer service issues were cited as the most commonly reported problems.
Virgin Media saw its volume of complaints rise during the year, from 2010's 0.03 complaints per 1,000 customers, to 0.07 by the most recent fiscal quarter. However, the firm was named as the UK's least complained about internet provider.
Ofcom compiles its data based on the number it receives directly, rather than the amount received by individual providers. Its quarterly feedback aims to guide consumers and incentivise service providers.
TalkTalk's broadband service attracted the most negative feedback during the first three months of the year, with Ofcom reporting 0.81 per 1,000 customers. By the final fiscal quarter, the figures dropped to 0.55.
"It's encouraging that complaints continue to come down," TalkTalk said in a statement. "Our own data shows ongoing improvement with a 40% year-on-year reduction in customer service calls and 75% of calls now being resolved on first contact.
"We remain committed to providing good service and best value and, while there is clearly more work to be done, we're pleased that customers are starting to see the benefits of the changes we continue to make."
Ofcom previously fined TalkTalk and its Tiscali UK subsidiary £3m - the largest penalty the regulator has ever handed out - for incorrectly billing more than 65,000 customers.
The company has since given out more than £2.5m in refunds and goodwill gestures. The Tiscali merger of 2009 was cited as the source of many of the problems experienced by TalkTalk users.
O2 remained the least complained about mobile service provider throughout 2011.