The Manchester United and England forward has been to two World Cups, in 2006 and 2010, though he faced injury problems in the buildup to both tournaments and failed to score in Germany and South Africa.
Having struggled to make an impact previously, the 28-year-old believes that the tournament in Brazil could be the opportune moment to prove his worth.
"Obviously I've been here before and I've said what I can deliver and do and it hasn't happened," Rooney told reporters. "For me personally, I feel that at the World Cup in 2018 I'll be a bit older then and it will be a little bit more difficult for me to impact in the way I believe I can do.
"So I believe this is really the last big one I feel that I can get the best out of me. I feel ready and fresh and as good as I can do going into this tournament. I believe this is the one that I have to show what I can do and I believe I'm in the best possible condition to do that. I'm ready for it, I'm excited for it and there will be no excuses this time.
"I believe we can go far — our aim is to win the tournament. That's what we're preparing for and that's what we're hoping for — and, with a little bit of luck, we could do it."
Rooney missed the end of the Premier League season with United through injury but insists he is now fully fit and ready for the World Cup.
"I feel good. I'm fully fit and took part in the full session on Monday," he said. "I have done on Tuesday and Wednesday as well so I feel good and ready to do everything. Obviously I missed the last few games of the season and I wanted to make sure that I was ready and available to train when the team met up.
"That was the reason behind [bringing fitness trainers on vacation] and it certainly helped me get up to speed with it and to be able to join in with the team on the first day."