Sean Casey said he will fight to get "Catfish," who he has owned for four years, back, WDAF reported.
Animal control also took three snakes and a rabbit from the home.
The house belonged to Casey's grandmother, who is in a nursing home. A trustee who owns the house evicted him, WDAF reported.
Animal control officers needed to call an animal rescue group to help remove the 200-pound reptile. The alligator was about 18 inches long when Casey got him.
"This thing was massive in size, and it took over four of us to handle this," James Donovan, with KC Animal Control, told WDAF.
Casey said he will fight to get back Catfish, who he called a harmless pet who enjoyed eating chicken nuggets, steak and fish, WFAD reported.
"He was like a dog. I don't think he knew he was an alligator. I tell people all the time I've got an alligator who can't swim. He is scared of the dark and scared of thunderstorms," Casey told WFAD. "I built him a ramp to get back in his tank because he is a big lizard. He was going to come out and play. He liked to come out and play. Oddly enough he liked to come sit on my lap."
However, alligators are a prohibited exotic animal in Kansas City and Catfish is in the care of an exotic animal rescue group, WFAD reported.