The village name is probably derived from a Frankish settler called Thelo or Thilo. During the Middle Ages, Thelenberg was part of the Electorate of Cologne and Amt of Altenwied and was also part of the Honnschaft of Schöneberg. According to a 1660 survey by the Elector of Cologne, Maximilian Henry, Thelenberg had four farms. In 1787 there were eight houses and 31 inhabitants.