The drop in profits came as revenue last year increased to $4.86 billion, up from $4.73 billion in 2012.
"Last year's financial results were affected by an increase in nuclear outage activities that were, in part, for the investments required to extend operations of our nuclear facilities as well as for emergent repairs," president and chief executive Tom Mitchell said in a statement.
The utility said total electricity generated in 2013 of 80.3 terawatt hours was down slightly from 83.7 TWh in 2012 due to lower nuclear and thermal generation, partially offset by higher hydroelectric generation.
Nuclear power amounted to 44.7 TWh in 2013, down from 49 TWh in 2012 due to extensions to planned outages at the Pickering and Darlington Nuclear generating stations.
Thermal generation decreased by 1.3 TWh to 2.8 TWh from 4.1 TWh in 2012 due to the end of operations using coal at the Lambton and Nanticoke generating stations.
Hydroelectric generation increased to 32.8 TWh from 30.6 TWh due to higher water levels and the addition of the Niagara Tunnel.