The final result shows that 70 percent of voters said no to the proposal.
Advocates of increased neutrality - led by the right-wing populist Swiss People's Party, which includes members with pro-Russian sympathies - believe the government has moved too close to the EU and NATO.
If voters had approved the proposal, it would have prevented Switzerland from participating in punitive measures against other countries, unless these were decided by the UN. The issue was raised in connection with the country's joining EU sanctions against Russia.
Within Switzerland's direct democratic system, citizens typically vote four times a year on various local and national issues.
