The Mughal Emperor taken prisoner by Nadir Shah was:

Muhammad Shah was the Mughal emperor imprisoned by Nadir Shah.

Key Points 

• Nadir Shah was the ruler of the Persian Empire.
• He belonged to the Afsharid dynasty.
• He was an ingenious military man who created a vast empire out of his sheer tactics and brilliant military reformations.
• He was attracted towards the wealth of India.
• He invaded India in 1739 AD during the reign of the Mughal Emperor Muhammad Shah.
• Nadir Shah and his army defeated the Mughals in the Battle of Karnal in 1739 AD.
• After the battle, the Mughal Emperor Muhammad Shah was imprisoned by Nadir Shah.
• Nadir Shah sacked and plundered the city of Delhi and took away immense amounts of wealth.

• He also took the famous Peacock throne built by Shahjahan along with the legendary Koh-i-noor apart from the money and jewels. 

Hence, we can conclude that the Mughal emperor imprisoned by Nadir Shah was Muhammad Shah.

Additional Information 

• Bahadur Shah I (1707-1712 AD):
  • Muazzam ascended the throne and assumed the title of Bahadur Shah, at the age of 63.
  • He was given the title of “Shah-i-Bekhabar” by Mughal historians like Khafi Khan.​ 
• Jahandar Shah (1712-1713 AD):
  • ​Jahandar Shah was the first puppet ruler in Mughal India.
  • He was supported by Zulfiqar Khan (wazir) who had the reins of the executive in his hands. 
• Farrukhsiyar (1713-1719 AD):
  • ​He ascended the throne with the support of the Saiyyad brothers – Saiyyad Abdullah Khan (Wazir) and Hussain Ali Khan (Mir Bakshi). 
  • In 1717 CE, Farrukhsiyar granted many trading privileges to the East India Company and also exempted customs duties for its trading through Bengal.