New Zealand, which administers Tokelau, funded a $7m (£4.3m) solar project.
Solar grids were constructed on the three atolls, with the last completed earlier this week.
"The Tokelau Renewable Energy Project is a world first. Tokelau's three main atolls now have enough solar capacity, on average, to meet electricity needs," New Zealand Foreign Affairs Minister Murray McCully said in a statement.
"Until now, Tokelau has been 100% dependent upon diesel for electricity generation, with heavy economic and environmental costs," he added.
Project co-ordinator, and PowerSmart MD, Mike Basset-Smith said that the move represented a "milestone of huge importance" for Tokelau, as it would now be able to spend more on social welfare.
The remote islands of Tokelau lie between New Zealand and Hawaii.