The City captain netted his side's third at The Hawthorns after Yaya Toure’s double had put the visitors in control before the break.
City's title challenge had been written off by some before the start of the campaign but Kompany insists his side have offered the perfect response.
"I think, for us, we have something to prove," the Belgian told Sky Sports. "Last season was below what we are used to and, if you were to look at the training sessions we did - especially last week - it's a team that has great intent.
"Obviously there are a lot of favourite teams now - we're not part of it I've heard!
"It's something that gives us extra motivation. We came out here today knowing that we had a point to prove."
Asked whether he needed to answer his own critics after a disappointing campaign last term, Kompany added: "More than anyone else, I think. I've worked hard.
"Sometimes you get judged on how you finish a season. Until November I was having a good season, but it didn't matter in the end because we didn't win anything
"I think as a team we all have to improve this season, but for me I just want to get back to my best level and games like today are giving me the confidence.
"I'm extremely hungry for more silverware and extremely hungry for great performances."
