Last week, the LaLiga outfit beat Russian side CSKA Moscow to secure a four-year deal for the 22-year-old from Swiss club FC Zurich.
The left-footed forward made his bow for the Valencia side in a friendly win over Real Zaragoza on Saturday.
Dwamena, who penned a heartfelt message to his former club Zurich, has been handed the no. 20 jersey for the 2018-19 campaign, and will hope to form a fearsome attacking trident with countryman Emmanuel Boateng - set to return to first-team duties - and Nigeria's Moses Simon.
He has been capped three times by the Ghana national