Rev Caspar Bush of St Euny's church in Redruth posted a message to the social media site explaining that Terry Filer had died with no known friends or family.
Rev Bush said he has been overwhelmed by the response from local people, students of a college in nearby Falmouth and businesses in Redruth.
He told Premier: "I am happy to report we've had a wonderful response. It has been really heartening to see how much interest there has been."
In addition to people promising to join the congregation, there has been a particularly welcome offer which will mark the funeral as a truly Cornish occasion.
Rev Bush went on to say: "We also had a lovely offer from one of our best local pasty makers. (She) rang up to say 'I'm bringing you 75 pasties at 2 o'clock'.
"So now we know we're having a wake after the funeral too. It's really developed a life of its own."
For St Euny's church, the funeral has been turned into an opportunity to highlight the issue of loneliness in today's society.
Rev Bush is urging people to reach out and offer support to the vulnerable.
"Terry stands for a lot of people because loneliness is a massive social issue for our time," he said.
"There's a huge opportunity for the church (and) for all people actually to look out for people who we're aware of being on their own."
Thanks to Facebook, the pews at the funeral will be far from empty.
Rev Bush plans to use the eulogy to highlight the Christian message of God's love for each individual.
"Here is Terry who is a dearly loved child of God and we want to show solidarity with him in our shared humanity and in the hope God gives us in Jesus," he said.
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