Dolly (28) joins from French Ligue 1 side Montpellier while 32-year-old Alexander signs after a season in the Indian Super League with Odisha FC.
Both players have penned three-year contracts with Amakhosi, while Dolly has a two-year option to extend, with Alexander a one-year option.
Part of a Chiefs statement read: “Dolly was in France with Montpellier where he spent five seasons. Before moving to Europe, he played for Mamelodi Sundowns and Ajax Cape Town. The 28-year-old is a product of the School of Excellence. The winger will don jersey #10 for the next three years.
“Alexander joins Chiefs from Indian Club, Odisha, where he spent just one season. The player will be reunited with coach Stuart Baxter who was in charge of Odisha at the time. The hardworking midfielder will wear jersey #17 at Chiefs.
“Dolly will reunite with Khama Billiat and Leonardo Castro after playing with them in the same team in 2014/15, while Alexander will be happy to reconnect with Sifiso Hlanti, Kgaogelo Sekgota, Brandon Peterson and Phathutshedzo Nange who were his teammates at Wits just over a year ago.
“Both players have represented Bafana Bafana with Dolly appearing 19 times in national colours and Alexander has 6 caps to his name.
“Alexander has started training and Dolly will start his training with Amakhosi on Thursday.”
Itumeleng Khune, Lebogang Manyama, Khama Billiat, Bernard Parker and Ramahlwe Mphahlele have, meanwhile, all been handed contract extensions.