Chelsea followed up last Sunday's Capital One Cup final victory over Tottenham with a 1-0 win at Upton Park to consolidate their five-point lead over second-placed Manchester City.
Goalkeeper Courtois was integral to the success, secured by Eden Hazard's first-half header, making a number of key saves, and reckons the win was crucial in the title race.
"Those games define if you can be champion or not," Courtois told Chelsea TV.
"A lot of teams lose points here
It was a hard game and we came out with a victory.
"At this stage of the competition of the league an away win like this is really important to be champions in the end.
"Those games decide if you will be champions or not.
"If you lose points here then you know City is back at two points (behind).
"We did well, so we have to continue in that way and hopefully at the end of May we can lift the trophy."
The Belgium goalkeeper thinks the performance, just a few days after the Wembley win, shows Chelsea have the desire to add a first Premier League title in five years to their League Cup success.
"The motivation is to be champions," added Courtois, who won Spain's Primera Division last term while on loan at Atletico Madrid.
"Every player will be motivated if you know you're playing to win the title.
"Three days after Wembley, okay maybe for some players it's hard, but everybody showed that we are great professionals who, after winning a title, want more and more."
Courtois, restored after Petr Cech played at Wembley, saved Chelsea time and again as West Ham were thwarted.
He has displaced Cech as first choice this term and Chelsea manager Jose Mourinho revealed on the eve of the match he would not stand in the Czech Republic goalkeeper's way if he asked to leave this summer.
Courtois said: "He's also one of the best keepers in the world
We train really well together.
"I can still learn from him
Maybe some things he can learn from me.
"Obviously I prefer if the team plays well, we defend well and we don't need my saves
(But) I help the team like every other player."
Chelsea, out of the FA Cup, next play Paris St Germain next Wednesday in the second leg of their Champions League last-16 tie.
The Upton Park win was important for Chelsea after dropping points at home last time out in the league, according to Hazard.
Hazard told Chelsea TV: "Before the game we said after the draw against Burnley we needed to take three points away
After a bad result it's always good to win one game.
"We had a lot of opportunities, they had a lot of opportunities.
"I scored with my head.
"It's not every game, but when I can, I close my eyes, I touch the ball and the ball goes in the net."
West Ham defender James Collins, who replaced Winston Reid (hamstring) after eight minutes, rued an opportunity missed.
He told West Ham TV: "We're disappointed in the changing room, to be honest.
"We thought we had the chances to get a point or even win the game.
"Earlier on in the season we were sticking them away, unfortunately at the minute we're not.
"We're in a good spot, we're 10th in the league, 39 points on the board and we've got some winnable games when we get going again
So we've got to kick on."
Source : PA
Source: PA