Johnston's tour begins Tuesday in Halifax where he will deliver the keynote address at a meeting of the World Federation of Colleges and Polytechnics.
On Wednesday, he will visit a lobster pound in Yarmouth and haul lobster traps in the harbour with a fisherman before attending a reception in his honour.
Johnston will tour a historic Acadian village on Thursday in West Pubnico and make a stop at a seafood harvesting and processing plant.
He will also present various awards to youth and volunteers during his Nova Scotia visit before attending the Governor General's Canadian Leadership Conference in Halifax beginning Friday.
The two-day conference is expected to attract representatives from the government as well as leaders in business, labour, academia and community groups.