Burkina-Faso, Costa Rica, Croatia, Libya and Vietnam were elected non-permanent members of the UN Security Council on Tuesday for two years beginning Jan. 1.
Five non-permanent seats on the 15-member Security Council were up for grabs.
Burkina-Faso, Libya and Vietnam, which had the support of their respective regional groups, were elected by secret ballot in the first round of voting by the 192-member General Assembly to succeed the Democratic Republic of the Congo, Ghana and Qatar.
Libyan UN Ambassador Giadalla Ettalhi hailed his country's election.
"I think for us it has a very important meaning, being elected to the Security Council by a very high score," he said. "It means we are back in the international community. All the problems we have faced in the past are now behind us."
Libya had long been considered an international pariah after it was censured by the Security Council for its refusal to surrender Libyan suspects in the 1988 bombing of Pan Am Flight 103.
But earlier this month Washington said it would not campaigning against Libya's bid to join the council, in what was seen as another move to end the oil-rich north African state's diplomatic isolation.
In May last year, Washington renewed diplomatic ties with Libya, ending a 25-year-old diplomatic battle with Libyan leader Muammar Qaddafi and taking the country off the US list of states accused of supporting terrorism.
The move followed Qaddafi's announcement that he was renouncing a weapons of mass destruction program.
US deputy ambassador to the UN Alejandro Wolff said his delegation looked forward "to working with all new members that are elected."
"On a personal note, I noticed there were family members of the Pan Am 103 tragedy and I know others were watching," Wolff said. "Their presence was felt here today. I felt it like no other delegation."
Libyan Abdelbaset Ali Mohmmed al-Megrahi was convicted in 2001 by a trio of Scottish judges sitting in a special court in the Netherlands of blowing up Pan Am Flight 103 by means of a bomb smuggled on board in a suitcase. He was sentenced to 27 years in jail.
"I'm glad we got elected in the first round," Vietnamese UN Ambassador Le Luong Minh said. "That reflects the trust of member states in our ability and responsibility to fulfill our obligations. We will be a responsible member of the United Nations and of the council."
Burkina Faso received 185 out of 190 valid ballots cast, Vietnam 183 and Libya 178.
Costa Rica and Croatia were elected in their respective groups after their respective opponents -- the Dominican Republic and the Czech Republic -- withdrew in the third round following two earlier inconclusive rounds of balloting.
The Security Council is made up of five veto-wielding permanent members -- Britain, China, France, Russia and the US -- and 10 non-permanent members, elected every year by groups of five for two-year mandates that cannot be immediately renewed.
Non-permanent members South Africa, Belgium, Indonesia, Italy and Panama will stay on the council until the end of next year.