The South Pacific territory – comprising the three atolls of Atafu, Nukunonu and Fakaofo – had been dependent on diesel to generate electricity.
New Zealand, which administers Tokelau, funded a $7m (Â£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.
Most of the 1,500 islanders live by subsistence farming, with thousands of others choosing to settle in New Zealand or neighbouring Samoa.