A scrambled goal from skipper Johnny Mullins in the 64th minute sent the Rotherham faithful wild and victory was sealed in injury time when Lee Frecklington condemned Aldershot to non-league football next term.
"We were expected to achieve it and we did," he said. "It's a fantastic achievement by everyone from the chairman to everyone inside the football club and the supporters as well of whom I have often spoken and they were at their best and they have helped us again.
"A lot of people doubted the squad but we kept believing and we always believed over the 46 games. We have missed out on champions, but we proudly sit in second.
"It was always the objective to lead Rotherham to League One and its now about enjoying what we have achieved and collectively enjoying it by everyone inside Rotherham United, the fans and the town who can all see what we have done."
Goalscorer Frecklington added: "There's no greater feeling in football than winning promotion. It was an important goal to score and it was great to score it, but once that first goal went in we relaxed and we knew we would be all right."