Mokoena will have the honour of leading out the Bafana Bafana when the competition is played on African soil for the first time next year. The former Ajax midfielder feared staying at Ewood Park would put his place in Joel Santana's line-up in jeopardy after starting only nine league games last season.
Mokoena, who has signed a three-year contract with Portsmouth, said: "South Africa staging the World Cup is a dream come true but it starts now with Pompey. I need to do the business with the team and move onto the national team.
"I need to work hard to earn my place, we all do. We cannot take our places for granted just because we are the host nation. The World Cup is coming, I need to be playing as much as I can. It's all about working hard and showing the manager that I really want to be in the team."
Mokoena, who led the side to the semi finals of this year's FIFA Confederations Cup, expects the competition to be a resounding success and has called on South Africa's neighbours to show their support.
"We are not only representing South Africa, we are representing the African continent," he said. "It's not only about South Africa, we need all the support we can get from African countries. This is important for all of us, we are carrying the flag.
"We realise the world is watching - but I'm sure we'll be ready to make sure it becomes a successful World Cup in Africa. We have all seen the World Cup, it is our chance to be part of that now and to host it is fantastic. It is a great challenge both on and off the pitch."
No African nation has ever lifted the FIFA World Cup and South Africa failed to get beyond the group stage in their two previous appearances at the finals in 1998 and 2002. Mokoena, who has gone on to become South Africa's most capped player with 90 appearances since replacing the popular Lucas Radebe as captain, said: "As a football team, we'll be going out there and showing the world we have talent.
"We did well in the Confederations Cup and next year we will be going out there to compete with excellent players. It's a World Cup - we know it is a totally different ball game to the African Cup of Nations and the Confederations Cup. But we are the hosts. This is a boost for us and it's going to be hard - so we must go out there and do the business."
Mokoena has joined a Portsmouth team who are facing a battle to hold onto their top flight status after losing star players Glen Johnson, Sol Campbell and Peter Crouch during the close-season.
But the 28-year-old is relishing the challenge, saying: "I have been waiting a long time to play for this club. A few of the established players have gone but Pompey are an established team. It is going to be a challenge but I am sure we can do well."