Pybus has signed a two-year contract with the Titans after resigning as Middlesex coach.
The club released a statement confirming the signing of the former Middlesex coach, who won the domestic Supersport Series championship with Nashua before resigning to join the English County Championship side.
"Richard Pybus has been re-appointed as the coach of the Nashua Titans," the statement read. "Pybus has signed a two-year contract."
Englishman Pybus handed in his resignation at Middlesex after just five months in the job, although the Nashua statement stresses the Titans vacancy had nothing to do with his decision.
"Pybus's resignation at Middlesex came as a complete surprise to the Titans and his reasons for his resignation, cited as personal, were completely unrelated to the vacancy," the statement continued.
Chairman of the board of directors, Andy O'Connor, also expressed his pleasure at the appointment.
"The re-appointment follows a protracted and comprehensive process during which a number of high-profile applicants were considered," he said.
"The position was offered to an individual in June, who informed us at the last minute he could no longer accept the position. This resulted in a second round of interviews in July."
O'Connor is now hoping the coach can repeat the success achieved in his first spell with the franchise.
"Upon learning he was returning to South Africa, the Titans expressed a keenness to re-appoint him." O'Connor said.
"We believe his track record speaks for itself. During his two-year reign the Titans have shared and won the SuperSport Series in emphatic style. We are confident he will continue the winning ways established in the previous two seasons with the Titans."
Pybus himself was delighted to be back with the Titans and was looking forward to getting busy with the players.
"There is much work to be done to maintain the fine form shown in the four-day competition and to improve the side's performance in the limited overs and Pro 20 competition." he said.