Yarde scored a try and set up another for the Exiles as they finished their Amlin Cup campaign on a high, despite being eliminated, against Bordeaux-Begles as they ran out 17-7 winners.
And Smith heaped praise on the young flyer and insisted Yarde was already up to the task of making the step up to international rugby.
He said: "Marland Yarde is an international winger, he is that now. He wouldn't be out of place on the left wing for England.
"He's a class act. Marland does all the tough work; he chases kicks like his life depends on it and he's got great urgency. He gets off the line in defence and when he's in space he's dangerous.
"He's really an electric player and I think Stuart Lancaster has a lot of great options, but I'm not sure there's many better than Marland Yarde playing in this league."