Brian Foster made the discovery while assessing how badly the water had damaged his house near Lake Houston, north of Houston, he said.
"I walked through the house and was looking at demo-ing the house, when I turned around and walked back through my dining room. I looked down, and there was a 10-foot alligator in my dining room," Foster told CNN affiliate KTRK.
Foster and his demolition crew spent the next few hours trying to lasso the gator and drag it out of the house.
Then, Wildernex Wildlife Control and local law enforcement officers showed up and started to wrestle with the reptile. They managed to get on top of it and tape its mouth shut before carting it away to an animal sanctuary.
Foster, who's from Louisiana, told KTRK he had to do a double take when he first noticed his scaly visitor.
"The homeowner's first thought was, 'Is this real or fake?'" said Constable Mark Herman of Harris County, Texas. "He was so disconnected from the fact that there could be an alligator in his home that he had to think for a second to see if his wife had bought a fake alligator or not."
Other alligator sightings
Foster isn't alone in his discovery. Other Houston-area homeowners have also returned in the wake of the hurricane to find uninvited house sitters, experts said.
"We are getting calls. We do know that there are large alligators in this area," said Jarred Pollard, one of the experts involved in the capture at Foster's home. "Now that the weather is better, we are getting a lot of calls for animals that have been displaced, animals getting into people's homes and attics."
Lily Thien of Missouri City, southwest of Houston, took cell phone video from inside her home as alligators casually sunbathed in her still-flooded backyard. In the video, shared on Facebook, Thien and her daughter watch safely from behind a window.
Asked if she's scared, Thien's daughter shakes her head no.
Local officials said it is common after floods for wild animals to make their way into civilization.
"Wildlife is either being displaced or caused to move around by Hurricane Harvey," Tom Harvey, deputy division director of Texas Game Wardens, tells CNN.
Texas Parks & Wildlife authorities warn residents not to approach wildlife, including alligators and snakes.
"The alligators aren't interested in people, they're just looking to find a safe place to say," Harvey said. "We've been posting a lot of information warning people that wildlife may have moved around and advising them on what they should do if they come in contact with alligators and the like."
In one case, the Game Wardens worked alongside Texas troopers to corral and relocate a 12-foot alligator displaced by Harvey in southeast Houston.
"This isn't like Florida, where you find gators in your pool," Herman said. "It's a rare event to happen upon an alligator here."