He’s not just man’s best friend — he’s an entire town’s.

Mellow the dog had walked the streets of Dupont, Pennsylvania, with his owner, Kevin Curry, twice a day since September 2019.

Tragically, the rescue pup was recently diagnosed with a fast-spreading lymphoma — so Curry led Mellow on one final lap Saturday as a farewell before he reaches “doggie heaven.”

“It is a heartwarming and heartbreaking story,” KJ Warunek, who lives in the area, told The Post on Tuesday.

“There were at least 25 people [on the first block]. When I looked to the next block, there was another 20. I’m going to say that was how the whole walk went.”

Warunek said Curry left a heartbreaking flyer in neighbors’ mailboxes, informing them about Mellow’s goodbye trot. He has been “slowing down” due to the terminal cancer, making it difficult for him to make the daily trek.

“Regardless of how well we know each other, you have made my life so much richer than any rescue dog could have hoped for,” Mellow “wrote” in the tear-jerker of a note that Warunek posted to a local Facebook page.

“I am so grateful to have such a caring neighbors and live in a community that looks out for one another so well,” the message continued. “I’m not sure when exactly I will go, but each day over the past few weeks has been a struggle for me to get around the neighborhood like I used to.”

“[I] would love to say goodbye face-to-face if you are available,” it continued. “Come out to pat me on the head or rub my belly and I will be forever grateful.”

The note included a map of the route and $5 to buy a gift for a dog or donate to charity.

Warunek said Mellow’s event was somber when she arrived with her husband, Mark. People were patting the pup and giving him treats.

“Others just stood in the back and cried, so as to not upset Kevin,” she recalled. “However, Mellow knew he was the belle of the ball — he pranced around.”

She said the neighborhood gave the greatest send-off the pup — and his owner — could have hoped for.

“He even got free ice cream at Choo Choo’s, our local shop,” she added.

Warunek said despite his illness, the pooch lived his best life with Curry.

“[Mellow] only has a few more days on Earth, but his dad gave him the best life when he adopted him,” she said. “And you can clearly see he was man’s best friend.”