Episode one of the show’s fifth season took a massive 17.3 million viewers, including 11 million 18-49s.
This represents the biggest figure for a single cable television broadcast, surpassing the 17.2 million viewers High School Musical 2 scored in 2007 on Disney Channel.
The Walking Dead already holds the record for the most-watched overall cable broadcast including time-shifted viewing, with a total of 21 million tuning for the season four premiere.
It is likely the season five opener will pass that mark, with a figure of around 22 million expected.
The show, which stars Andrew Lincoln as the leader of a group of survivors living in a world dominated by the undead, has been a ratings hit since season one, but has steadily built up steam with each new run. The season four opener took 16.1 million, previously its best single episode score.