The move has been blocked every year since 1993 by archrival China and its allies.
After hearing from representatives of more than 90 nations, a General Assembly committee rejected a bid for the question of UN membership for Taiwan to be added to the agenda for the assembly's 58th annual session, which opened on Tuesday.
The assembly's General Committee, a panel on which all 191 UN members have a voice, made the decision by consensus, with no formal vote.
Taiwan, which was making its 11th annual bid, has a population of more than 23 million people and has one of the world's largest economies.
The country, about the size of Switzerland, uses its economic influence to garner support from mostly tiny and impoverished UN members in Central America, Africa and the South Pacific.
But China, which views Taiwan as a breakaway province that must be reined in, has outmanoevered its rival.
The UN membership question has been a burning issue since 1949, when Chiang Kai-shek's Nationalist government lost a civil war to the Chinese communists but held on to China's UN seat even after fleeing to Taiwan.
In 1971 the General Assembly kicked out Taiwan and gave the seat to China instead.
The majority of UN members regard Taiwan as part of China although Taiwan has constantly argued it should have its own seat in order to take part in international organisations.