He told the club's official website: "There was interest from Leeds and Ipswich but I just felt like joining Forest was the right thing to do."
Commons, whose fee will be decided by a tribunal because he is under 23 years of age, joins from Stoke City on a bosman free transfer.
The youngster has signed a three-year deal with Forest and revealed that it was a dream come true to play for his hometown club who he actually played for as a seven year-old.
He told the Nottingham Evening Post: "It's a massive club with big-name players. It's going to be hard but I'm looking forward to the challenge.
"Forest had a great end to last season and I am joining a team capable of pushing for promotion."
Forest have also given a trial to South African midfielder Stanton Fredericks. The 26-year-old, who currently plies his trade at Kaizer Chiefs, is expected to play some part of Forest's tour in the USA in July.
Forest have however missed out on the signing of Matthew Spring from Luton after he decided to join Leeds United on a three-year deal.
Meanwhile, former Forest 'keeper Pascal Formann has joined neighbours Notts County on trial. He was released by the Reds at the end of last season after failing to impress boss Joe Kinnear.
Norwich manager Nigel Worthington has moved quickly to quash reports that Forest striker David Johnson could be on his way to Carrow Road in a £3m switch.
He said: "The reports about David Johnson are news to me - there is nothing in that at all. Even if it had been true, Norwich City Football Club would not be in a position to offer £3m for any one player."