The group said the split, which marked 50 days since it formed, was planned.
It also posted on Bit Torrent what it said would be the last of a string of data caches stolen from online sources.
Since its inception, LulzSec had stolen and published sensitive information from dozens of high profile organisations including Fox, PBS, Sony and the CIA.
The last cache contained troves of AT&T documents including information on its 4G LTE deployment, and details on some 90,000 IBM phones, internal emails, memos and reports.
Also stolen was an AOL internal technical document, and hundreds of thousands of usernames and passwords of which 200,000 were swiped from HackForums.net and 50,000 from unnamed video game forums.
HackFoums.net had reset user passwords.
The group’s actions had sparked the ire of other groups and individuals who claimed to have uncovered information on LulzSec members and provided the details to police.
Last week an affiliate of the group, Ryan Clearly, was arrested by Scotland Yard for computer crimes related to the LulzSec hacks.
Alleged details of the members had been posted publicly online in what is referred to as doxing attacks.
The group made no mention of the reported crackdown by law enforcement, and noted it hopes the online Anti-Security Movement campaign in which it participated would continue.
“Thank you for sailing with us. The breeze is fresh and the sun is setting, so now we head for the horizon,” the group wrote.