The 48 year old father and husband was stabbed to death by Khalid Masood while he was on duty at the Palace of Westminster.
Bishop of Southwark, Christopher Chessun, says the public support is symbolic in this time of mourning.
He said: "I hope that people will be encouraged that the human response in the context of one terrible act was many, many acts of goodness and kindness. It's a sense that the darkness has not triumphed and the light is still shining."
A large crowd including more than 5,000 police officers lined the streets as PC Palmer's funeral cortege traveled from the Palace of Westminster to Southwark Cathedral.
Bishop Christopher went on to say he hoped relatives of PC Keith Palmer would take comfort from shows of support on the day of his funeral, explaining: "Words cannot express all the human emotions. The physicality of people being there alongside the family is something which I hope will allow people to feel that they have played their part. "
While everyone had a chance to view the funeral procession, the late officer's ceremony was private. Around 50 members of PC Palmer's family attend the cathedral service, led by the Dean of Southwark.
Referring to the need to balance the private grief of relatives with allowing the whole nation to mourn, Bishop Christopher added: "There is of course the national focus on the private grief of a family - it's holding those two together.
"So, the journey through the streets of London across Lambeth Bridge and then to Southwark Cathedral will provide streets along which people can line and express their own feelings in a public way.
"Then, the service itself will have a note of intimacy about it and I hope that was a blessing for everyone present and especially for the bereaved family."