Several foreign players have withdrawn from the inaugural 100-ball-a-side competition due to the COVID-19 related challenges with the organisers announcing the replacements on Friday.
Former South Africa skipper du Plessis replaces Australia's limited overs captain Finch, who will be away with national team.
Du Plessis joins the likes of England all-rounder Ben Stokes, spinner Adil Rashid and Australia's Chris Lynn at the Superchargers.
"It is a real honour to lead Northern Superchargers in their first season. Playing alongside the likes to Ben Stokes, Adil Rashid and Chris Lynn alongside a number of talented young players will be really exciting. I can’t wait to get going in a few weeks time," du Plessis was quoted as saying on the The Hundred's website.
South African women's team player Laura Wolvaardt is in for star Australian wicket keeper batter Alyssa Healy at the Superchargers.
The Proteas are well represented as Suné Luus (Welsh Fire), Shabnim Ismail (Oval Invincibles) and Imran Tahir (Welsh Fire) have also signed up for the tournament.
The Hundred, which was postponed last year due to the COVID-19 pandemic, is scheduled to start from July 21 with the women's match between the Oval Invincibles and Manchester Originals in London.