| Najabat Ali Khan Bahadur | |
| Native Lang1 Name1: | নজাবত আলী খান |
| Native Lang1: | Bengali |
| Saif-ul-mulk (Sword of the Country) Suja-ud-Daulah (Hero of the State) Shahmat Jang (Arrow in war) | |
| Succession: | Nawab Nazim of Bengal and Bihar |
| Reign: | 22 May 1766 – 10 March 1770 |
| Coronation: | 22 May 1766 |
| Full Name: | Mir Najabat Ali Khan |
| Birth Date: | 3 March 1749 |
| Birth Place: | Murshidabad, Bengal, Mughal Empire |
| Death Place: | Murshidabad, Bengal, British India |
| Burial Place: | Jafarganj, West Bengal, India |
| Predecessor: | Nazim-ud-din Ali Khan |
| Successor: | Ashraf Ali Khan |
| Dynasty: | Najafi |
| Father: | Mir Jafar |
| Mother: | Munni Begum |
| Religion: | Shia Islam |
Sayyid Najabat Ali Khan Bahadur, born Mir Phulwari (Bengali: নজাবত আলী খান; 1749 – 10 March 1770), better known as Saif ud-Daulah succeeded his younger brother Nawab Nazim Najimuddin Ali Khan, after his death in 1766, as the Nawab Nazim of Bengal and Bihar.
He was the third son of Mir Jafar by Munny Begum. He was only seventeen when he was crowned as the Nawab. He reigned under the regency of his mother and died of smallpox on 10 March 1770, during the Great Bengal famine of 1770.
After the death of Najimuddin Ali Khan, his younger brother Najabat Ali Khan, better known as Saif ud-Daulah, succeeded him and was placed on the Masnad (throne) at the age of 17. The management developed upon his mother, Munny Begum. On 19 May 1766, a treaty was concluded in which the East India Company was to pay him the reduced stipend of 41,86,131 and 9 Anas (1=12 Anas), namely 17,78,854 and 1 Ana for the Nawab's household and 24,07,277 and 8 Anas for the support of the Nizamat.
Saif ud-Daulah was formally installed on the Khahar Balish, at Murshidabad Fort on 22 May 1766, which was confirmed by Mughal Emperor Shah Alam II on 27 June 1766. However real authority passed into the chamber of the Directors in London who considered that the Nawab and the Government's dignity still resided in the Nawab and his ministers.
In 1770, during Bengal famine of 1770, a great epidemic of small pox raged in Murshidabad and killing 63,000 of its inhabitants, one of them being Nawab Nazim Saif ud-Daulah, himself. He died on 10 March 1770. His mortal remains lie in the Jafarganj Cemetery in Murshidabad.
He was succeeded by his half-brother, Nawab Nazim Ashraf Ali Khan as the next Nawab.