The midfielder on Thursday morning joined Portuguese side Braga on a four-and-a-half-year deal.
Piazon joined Chelsea in the summer of 2011 and made just three senior appearances since, his sole Premier League outing coming in December 2012.
The Brazil-born winger enjoyed loan spells across Europe with Malaga, Vitesse, Frankfurt, Chievo and most recently Rio Ave.
Piazon's most success spells came in England in the Championship with Reading for a season and then Fulham for two.
An 18-month loan with Rio Ave - which saw Piazon rack up six goals across 29 games - has convinced Braga to make him their seventh signing of the season.
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