The Swiss came ahead of Denmark, Sweden, Austria and the United Kingdom, as northern European countries held the top five ranks in the World Energy Council's energy sustainability index for 2013.
China ranked 78th and the United States was 15th, according to the report by the WEC, a London-based group that promotes sustainable power.
Canada came in sixth and France was 10th, while the worst showing of all 129 countries was made by Zimbabwe.
Countries were also given letter grades for their performance in three categories: how well they manage their energy supply, how accessible and affordable energy is across the population, and how much of their power is derived from low-carbon renewables.
Only five countries received all A's — Switzerland, Denmark, Sweden, Britain and Spain.
"Switzerland continues to be the best in the world at limiting its impact on the environment with low levels of pollution and ultra-low emission energy infrastructure that uses fossil-fuelled power plants for only two percent of electricity generation," the report says.
Energy security is the country's "least-strong dimension because the country imports around half of the energy it uses," it says.
The Swiss face challenges on sustainability, however, over a decision to phase out nuclear electricity.
In the short-term, Switzerland is "likely to become more dependent on gas-fired electricty generation".
Elsewhere in the report, Benin and Zimbabwe received all D's. India, Lebanon, Yemen and Nicaragua also fared poorly with C's and D's.
China got an A for energy security but D's for the environment and affordability and equitable access to power.
The United States was a top scorer in security and supply but earned a C in environmental friendliness.
The report was based on interviews with more than 50 government officials, development banks and international experts from more than 25 countries, the WEC said.
Policymakers interviewed for the report urged more proactive energy policies, and called on the energy industry to help developed countries makes strides toward sustainable energy.
The report was released three weeks ahead of talks at the World Energy Congress, to be held in Daegu, Korea.