After finally agreeing personal terms with the Giallorossi, the Italy Under-21 international is set to spend the next five years at the Stadio Olimpico
As part of a complicated deal, the Rossoblu have also acquired 50 per cent stakes in Giallorossi youngsters Giammario Piscitella and Valerio Verre for a combined total of £2.3m.
Destro spent last season on loan at Siena, who took up their option of entering into a co-ownership agreement with Genoa earlier this summer.
However, both clubs subsequently agreed to sell the striker to Roma. The deal was initially held up by Destro's wage demands, but the 21-year-old revealed last week that a deal had been brokered that will bind him to the Stadio Olimpico until 2017.
The Italy Under-21 international netted 12 times in 30 appearances for Siena in Serie A last season and his fine form earned him inclusion in Cesare Prandelli's provisional panel for Euro 2012.