Mancini has spoken to Three Lions boss Fabio Capello about Johnson, who has eight caps and two goals.
Mancini said "We have the same opinion. We know he is an incredible player but a player like him should play very well every game, like Silva.
"He should be in the national team all the time."
Johnson doesn't do the normal. He is a spectacular player, a winger who draws you to the edge of your seat.
He also has an eye for a long-range shot, as he showed with his 90th-minute goal on Saturday — a dipping shot from 30 yards into the bottom corner of the Wolves net.
Mancini said: "One versus one he is incredible. Every time he takes the ball near the box or wide, we can score a goal or have a chance.
"Also when we went down to 10 men he went on the right and defended very well against Jarvis. He did well."