The wedding will be broadcast live on a 50 ft screen on the cathedral's grounds in partnership with BBC Wiltshire.
The screening will be part of a free royal wedding party on the cathedral's grounds which will include live music performances, arts and crafts for children and a chance to write good luck messages to the royal couple.
Canon Robert Titley from Salisbury Cathedral told Premier News Hour he hopes it will be a meaningful time for attendees.
"It will be a really enjoyable and potentially profound day for people all across the country. Church of England weddings are public events and we thought what better thing to do than to make this a very, very public event so people can watch it together," he said.
"We hope very much the service itself will be a moment when people can reaffirm the points of love and friendship in their lives. After the service is over there will be an opportunity for people to come into the cathedral to say a prayer and light a candle."
He said it's also one way to show locals are moving on from the ex-spy poisoning attack.
"People are getting on with lives very well here. But the wider perception is that Salisbury's reeling from this attack. I think we've bounced back very well and this is a way in which we can show that."
Those who want to attend are required to apply for a free ticket in advance.
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