Florek gave fans a heads-up this week via Twitter, Variety reported. NBC says his final episode will be broadcast in January.
Florek sent his message Tuesday: "Friday was the last day 4 Cragen/Florek. It was a sweet send off! But he'll live on in syndication land 4 evah!"
After training at Juilliard in New York, Florek, 63, built up a solid resume in theater and in guest appearances on TV shows ranging from "The Equalizer" to "Roseanne" as well as a 22-episode run in "L.A. Law" in the late 1980s and early 1990s.
Florek as Cragen was part of the original cast of "Law and Order" from 1990 to 1993 with occasional reappearances. In 1999, he returned to the franchise as the commander of the special victims unit.
The series, the longest-lived of the many "Law and Order" spinoffs, lost Chris Meloni, who played Detective Eliot Stabler, in 2011. Richard Belzer, whose character, John Munch, transferred from the Baltimore Police Department in "Homicide" to New York for "SVU," is also leaving.