The Argentine attacker, who has scored four goals in 10 A-League appearances since joining the Reds in August, has penned a fresh two-year deal.
26-year old Neumann was thrilled to commit himself to United's cause for the next few seasons as he continues to enjoy life in Adelaide.
"From the first day here everyone has been so good to me, the owners, management, the staff, the coaches and the players have accepted me so well but what has been amazing is the way the fans have made me feel so welcome and a part of the club so quickly," he said.
"Everything has been very good so far it's a great club and a great city and that's why I decided to stay for a longer time here. I now look forward to focus on my football and do my best for the team."