Wigan boss Uwe Rosler has vowed to dictate the terms of those he is prepared to let leave on short-term loan agreements.
Toby Alderweireld is convinced that joining Southampton was the right move, as he sought to make 'the best step'.
Juve will pay one million euros to loan the Brazilian-born Italian, with the option to buy worth six million euros, the defending Serie A champions said on their website.
The option is automatically exercised if Romulo plays in at least 60 per cent of Juve's official matches this coming season.
Juve become the ninth club on the resume of Romulo, who played for six different sides in Brazil before moving to Fiorentina from Cruzeiro in 2012.
He was loaned to Verona before making the move official last month but has now moved on again, given the opportunity to play in the Champions League with Juve.