[5]: 288 Najafgarh was named after Mirza Najaf Khan[6][7] (1723–1782) the commander-in-chief of the Mughal Army under the Emperor Shah Alam II.

[8][9] He marched several kilometres from the capital of Shahjahanabad to establish a military outpost, which would guard Delhi against attacks by British, Rohillas and Sikhs.

He built a strong fort,[10] in the suburbs beyond the capital city, and settled a small number of the Mughal here.

[16] After the defeat of the Mughal troops in 1857, Delhi came under the control of the British Empire in 1858.

[22] In 1947, Najafgarh became a part of independent India and fell under the union territory of Delhi.

[25] Najafgarh Drain, the continuation of the Sahibi River and an elongation of the Najafgarh Lake is the Indian capital's most polluted body of water[26] due to the direct inflow of untreated sewage from surrounding populated areas.

A January 2005 report by the Central Pollution Control Board classifies this drain, with 13 other highly polluted wetlands, under category ‘‘D’’ for assessing the water quality of wetlands in wildlife habitats.

[1] Schedule Caste (SC) constitutes 12.60% of total population in Najafgarh.

The Najafgarh constituency of the Delhi Legislative Assembly was created in 2008 based on the recommendations of the Delimitation Commission of India constituted in 2002.

[29] Kailash Gahlot of the Aam Aadmi Party has been its representative since 2015, defeating Bharat Singh of the Indian National Lok Dal.

The line was further extended to Dhansa Bus Stand in September 2021, thereby linking the interior rural areas of Najafgarh.