Palmeiras midfielder Danilo has completed his £18m move to Forest following a medical yesterday.
The 21-year-old has signed a six-and-a-half-year contract and becomes Forest's 24th new arrival since the club won promotion to the Premier League last year.
He is believed to have been chased by several clubs before choosing the City Ground based on advice from a new teammate.
Gustavo Scarpa also joined Forest from Palmeiras earlier this month, and has encouraged his compatriot that Nottingham is a 'great city' and that Forest have a 'quality squad.'
'I'm really happy to be fulfilling my dream of playing in the Premier League and playing for Nottingham Forest,' said Danilo.
'I learnt a bit about the history of the club and saw they had won two European Cups. I spoke to Gustavo Scarpa as well, and he told me that Nottingham is a great city and Forest have a quality squad with really good staff.
'I will show a lot of determination and a strong desire to win and will always look to do my best on the pitch to achieve positive results.
'I'm excited about getting started and meeting my new team-mates.'
Danilo is joining a Forest side on a three-match unbeaten run in the league which has lifted the club out of the relegation zone and up to 13th in the table.
Forest's sporting director Filippo Giraldi said: 'We are really happy to welcome Danilo to our club and to our city.
'He is a fantastic talent that will be a great asset for the present and the future of Nottingham Forest.'