No. He is from an independent Comic, which is amazing...much better than anything the Turtles ever did. Written by Stan Sakai.
At a comic convention Stan just happened to be placed by the TMNT booth and a collaboration was born, which Stan wrote a few stories with the Turtles in his book, and TMNT had Usagi in the cartoon, and I think the comic. Stan Sakai did some awesome stuff with the Turtles treating them more like real Ninjas.
Usagi Yojimbo is one of the longest running comic book series, that is written, drawn and inked by one guy. Please check it out.