Balfour Beatty will carry out overhead line works and J Murphy & Son the cable contract for the power line between Beauly and Mossford, near Garve.
Full construction works will start next month and see engineers begin dismantling the existing tower lines along the 26km route.
There task is to remove 177 towers and replace them with a single, higher capacity tower line of 97 towers.
David Gardner, director of transmission for SSE, said: “The existing tower lines have been in place for around 60 years and have served the area well, but with more renewable generators wishing to connect to the grid, it is now time for an upgrade.
“By placing these contracts now, we are aiming for completion of the line by the end of 2015 with further reinstatement works being completed in 2016.”
He added: “We are also in the process of awarding the forestry and civil contracts to local firms.”