According to Visual Capitalist, here is a list of the 20 largest megacities projected for 2100:

Rank Population (2100) City Country
#1 88.3 million Lagos Nigeria
#2 83.5 million Kinshasa DRC
#3 73.7 million Dar Es Salaam Tanzania
#4 67.2 million Mumbai India
#5 57.3 million Delhi India
#6 56.6 million Khartoum Sudan
#7 56.1 million Niamey Niger
#8 54.3 million Dhaka Bangladesh
#9 52.4 million Kolkata India
#10 50.3 million Kabul Afghanistan
#11 49.1 million Karachi Pakistan
#12 46.7 million Nairobi Kenya
#13 41.4 million Lilongwe Malawi
#14 40.9 million Blantyre City Malawi
#15 40.5 million Cairo Egypt
#16 40.1 million Kampala Uganda
#17 40.0 million Manila Philippines
#18 37.7 million Lusaka Zambia
#19 36.4 million Mogadishu Somalia
#20 35.8 million Addis Ababa Ethiopia

 

Read the full article on Visual Capitalist.