Peter Terrence Jones, who is 28, entered the plea Thursday to 25 of 26 charges.
One of the counts had previously been withdrawn by the Crown.
Court heard that fires were set at several locations last year, including the airport, a rail yard, a welding shop, a cabinet shop, a park, an RV business and a fertilizer company.
Jones was initially arrested in November in relation to some of the fires, then arrested again last month following a search of his home and investigations into other blazes.
Jones remains in custody and will be sentenced April 14. (CHED)