A six-year-old US boy has celebrated the completion of a year-long chemotherapy treatment by ringing his hospital’s official “congratulations” bell.

Video of Jimmy Spagnolo ringing the bell and leaping about excitedly, waving his arms and dancing, was posted to the Children’s Hospital of Pittsburgh Facebook page late last week.

The video has since been viewed hundreds of thousands of times, with Facebook users joining the young boy in commemorating the milestone.

“The bell signifies so many emotions – it can signify the sound of tears, strength, fear, courage, doubt, satisfaction, relief and happiness all coming through as one as people around them cheer this accomplishment,” the post reads.

“The sound of that bell resonates in more ways than one. The emotion in the room is just unbelievable.”

On February 2, Jimmy completed his latest round of chemotherapy, aimed at shrinking an inoperable brain tumour, a Facebook page launched by his parents explains.

Jimmy was diagnosed with the tumour at four months and has since received multiple rounds of treatment.

The tumour has shrunken, however a number of “spots” appeared during a scan back in September. His parents nevertheless remain hopeful.

“(He) is a walking miracle that has beat every odd,” the page reads.

“If you were to meet him in passing you'd never know of his battle with cancer because he looks like a normal little boy, but in all truth he is full of love and is a blessing to this world.”