French forward Haller, signed from Eintracht Frankfurt in the close season, put the Hammers ahead in the 24th minute, sliding the ball home from close range after a wonderful cross from Arthur Masuaku.
The goal makes it three goals in two games for the club's record £45 million signing who opened his account with a brace at Watford last week.
Norwich, who have now suffered three defeats in their opening four games, should have pulled level in the 31st minute but Todd Cantwell put a header from close range wide, after a superb run down the flank from Max Aarons.
The Canaries then suffered a blow when captain Christoph Zimmermann was forced off with an injury following a strong challenge from Haller.
Ukraine international Yarmolenko doubled the lead in emphatic fashion with a fine left-foot volley from outside the box in the 56th minute.
"I think it was a massive performance as we played against a very good team who had played well against Chelsea and Newcastle. Tim Krul was their best player on the pitch. He played an unbelievable game," said West Ham manager Manuel Pellegrini.
"Sebastien Haller is a complete player. He scores goals but works a lot for the team as well. He will continue improving in every game."
Norwich manager Daniel Farke was unhappy that there was no sanction for Haller's challenge on Zimmermann.
Farke said: "This is a game where VAR didn't work. There was a nasty tackle against [Zimmermann] and it wasn't even given as a free kick. Then a few minutes later my centre back wasn't able to spring back and block the cross [for West Ham's first goal].
"My centre back is now in hospital. My feeling was this made the difference. I'm a friend of VAR but on this day it didn't work"