The company, which began in a suburban Auckland garage in 1992, employs around 40 full-time staff and a network of around 200 interviewers across the country.
The acquisition by Synovate comes as the Aegis-owned firm looks to expand further into New Zealand.
In April, Synovate Australia and New Zealand opened an office in Wellington. It already has a presence in Auckland through sister company Synovate Aztec.
Robert Lerwill, the Aegis chief executive, said: "Research Solutions is a highly regarded business which will fit well with Synovate’s brand and culture.
"By enhancing our capability in New Zealand, we will be able to offer a broader service to all our regional clients, to the benefit of Synovate and clients alike."
The acquisition by Synovate comes as the Aegis-owned firm looks to expand further into New Zealand.
In April, Synovate Australia and New Zealand opened an office in Wellington. It already has a presence in Auckland through sister company Synovate Aztec.
Robert Lerwill, the Aegis chief executive, said: "Research Solutions is a highly regarded business which will fit well with Synovate’s brand and culture.
"By enhancing our capability in New Zealand, we will be able to offer a broader service to all our regional clients, to the benefit of Synovate and clients alike."