The new two-year pact, which has an option for a third, replaces Katz's existing two-year overall deal with 20th TV, which had another year on it.
"Even has done a fantastic job on '24'," 20th TV president Dana Walden said. "It's clearly such an important series for the studio, so we found it to be a very good business decision to (secure) every writer who is important to the series for as long as posasible, and Evan is at the top of that list."
Katz worked on several series at Paramount Network TV -- UPN's "Special Unit 2", which he created, "JAG" and "Seven Days" -- before he joined "24" at the beginning of the second season in 2003.
"The show's been very good to me in every way," Katz said of "24." "It's the first time I've been on a show that is an out-and-out commercial and critical success and has created a cultural footprint.