Italy had taken the lead in the second minute through Riccardo Orsolini, but Paul Sampson's side bounced back in style to reach the final of the competition for the first time in England's history.
England launched a remarkable comeback after the interval, with new Liverpool signing Solanke scoring his first goal of the game after 66 minutes.
Sheyi Ojo's cross was palmed out by goalkeeper Andrea Zaccagno to Solanke for a simple finish and Ojo was again involved as England took the lead.
Everton attacker Ademola Lookman slotted home after Italy failed to deal with another Ojo centre, then Zaccagno was beaten too easily by Solanke's 25-yard drive as England wrapped up the match with two minutes to go.
In the first semi-final, Venezuela are through to a maiden final in any age group by triumphing 4-3 on penalties, with the new ABBA shootout system used after a 1-1 draw.
Uruguay's Nicolas De La Cruz gave his side the lead from the penalty spot, but Samuel Sosa hit a stunning free-kick to level the scores in the 91st minute and neither team could break the deadlock in extra time.
Captain De La Cruz was the villain for Uruguay, goalkeeper Wuilker Farinez blocking his kick with his right leg to send Venezuela through to a historic final in Suwon on Sunday.