Alamrhum Tuanku Jaafar Ibni Almarhum Tuanku Abdul Rahman, GCB was the tenth Yang di-Pertuan Agong (equivalent to High King) of Malaysia from 26 April 1994 until 25 April 1999 and the tenth Yang di-Pertuan Besar of Negeri Sembilan.
The Undang Yang Empat (ruling chiefs of the state) unanimously decided on Tunku Muda Serting, His Highness Tunku Ja’afar ibni Tuanku Abdul Rahman, who was 44 years old at the time, to succeed his elder brother as the Yang di-Pertuan Besar of Negeri Sembilan. This proclamation was made by Dato’ Undang Luak Jelebu, Dato’ Abu Bakar bin Ma’amor, at Balairung Seri Istana Besar Seri Menanti. Tuanku Ja'afar ascended the throne as the 10th Ruler of Negeri Sembilan on 18 April 1967.
Tuanku Ja'afar became the tenth Yang di-Pertuan Agong of Malaysia from 26 April 1994 until 25 April 1999 succeeding Sultan Azlan Shah of Perak. He was succeeded on the post by Salahuddin Abdul Aziz Shah of Selangor.
He died on 27 December 2008 and was buried at the Seri Menanti Royal Mausoleum at Seri Menanti on 29 December 2008.