Ben Bird made his favourite customer a promise: "Live to be 100 and I'll bring you a cake for your big birthday."
And when Dorothy Ballard reached the milestone this week and received a telegram from the Queen, Ben kept his word.
The binman walked up her garden path with a surprise birthday cake topped with three lit candles ready for her to blow them out.
He sang 'Happy Birthday to You' along with two colleagues.
Video from BPM Media:
More than two million people have watched Ben's act of kindness online.
Dorothy's granddaughter Katy Smith said: "My heart melted."
Father-of-two Ben has been collecting Dorothy's rubbish for more than eight years, and says he always spends ten minutes chatting with her.
Dorothy has lived in the same road in Birmingham for 74 years and used to work at the Tomkinson carpet factory.
Katy Smith, Dorothy's second eldest great grandchild, said: "My great gran always speaks so highly of her binman Ben.
"So I messaged him to thank him that he made her day.
"We all feel very blessed to have her, she has a great sense of humour and is loved by so many. We treasure every moment."
Given the many negative headlines about binmen in Birmingham in recent years following lengthy strikes and rubbish left on streets, Ben said it was wonderful to have inspired a positive story.
"It's just nice for everybody to talk about.
"We have deadlines to meet on our round, but my colleagues carry on and let me catch them up - I could not pass Dorothy's house without stopping to speak to her.
"A magazine said it would pay me £100 for the story, but I asked them to donate the money to the Midlands Air Ambulance.
"I could not possibly take it myself."