The male Shar-Pei crossbreed was found tied to a railing outside Ayr station on January 2.
The suitcase included the dog's pillow, toy, food bowl and food.
After Kai's story was publicised around the world the Society for the Prevention of Cruelty to Animals (SPCA) in Scotland was flooded with offers to take him. The charity chose Ian Russell as his new owner.
Russell, 52, was selected out of hundreds of people who volunteered to re-home Kai.
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"I'm over the moon and very shocked that I was chosen out of everyone who wanted him," he was quoted as saying by the BBC.
"My Dalmatian named Mica passed away just before Christmas and I was left heartbroken. I had her for 15 years and she was the apple of my eye. We pretty much spent 24 hours a day together.
"When I heard about Kai I knew the little guy needed a break but I never thought in a million years I'd get him."
"Fast forward a few weeks and here I am taking him home. I honestly think it was meant to be," he said.
The charity's senior animal care assistant, Alan Grant, said that offers to re-home Kai had come in from around the world after his story was reported across the international media.
"We were overwhelmed by offers of new homes for Kai from places as far away as New York, Los Angeles, France, Spain and even the Philippines," he said.
"Kai's story was really sad and many people likened him to Paddington Bear given he was found alone at a railway station with his suitcase."
The Scottish SPCA said it was still investigating the circumstances which led to Kai being abandoned.
Last month, a woman came forward to say she left the dog tied up at the railway station because she believed it had been stolen.