While Singh has been associated with the party since its inception, Sushil Gupta is a Delhi-based businessman and N D Gupta a chartered accountant.
The decision was taken at Chief Minister Arvind Kejriwal's residence in a meeting attended by around 56 party MLAs.
The party's highest decision making body, the Political Affairs Committee (PAC), met soon after and formally approved the decision.
"Sushil Gupta has made big contributions in the education and health sectors in Delhi and Haryana. He provides free education to 15,000 children. Narayan Das Gupta is the former president of the ICAI (Institute of Chartered Accountant of India)," Deputy Chief Minister Manish Sisodia told reporters.
Disgruntled leader Kumar Vishwas, who was angling for a RS slot, did not attend the PAC meeting. He is a member of the PAC.
Elections to three Rajya Sabha seats from Delhi would be held on January 16. The AAP, which enjoys a brute majority in the 70-member Delhi Assembly, is set to win all three seats.
The last date to file nominations for the three Rajya Sabha seats is January 5.