The 27-year-old Brazilian, who has joined French champions PSG from Chelsea for £50million, made a bright start to the World Cup finals and scored a sensational winning free-kick in the Selecao's quarter-final victory over Colombia.
But everything that could go wrong did go wrong in the semi-finals, with Luiz drawing heavy criticism for his performance as he captained Brazil to a humbling 7-1 thrashing by Germany.
Luiz has had time to "digest" the fall-out from that embarrassing night in Belo Horizonte and is now keen to help PSG in their double aim of winning a third straight league title and claiming the European Cup for the very first time.
At his official unveiling, he said: "If the World Cup had finished at the quarter-final stage then you wouldn't be asking questions about my ability.
"I've had time to digest the end of our World Cup and now I'm ready to do everything to help PSG.
"I feel privileged. I'm part of a fantastic team in which everyone has something to teach me. It's wonderful to be part of this project.
"I am very happy to have joined a big club and I'm just eager to start playing."
Luiz will link up with Brazil team-mate Thiago Silva at the Parc des Princes and, although the former is well-known for bombing forward during matches, he is convinced he will form an effective centre-back partnership with his friend.
He added: "Brazilian defenders play for all the best clubs! Thiago Silva and I are very good friends, we understand what the other is thinking with one look and we respect each other.
"We trust each other and will give our all out on the pitch.
"But I am ready to help out in any position, it's not up to me to choose, I just play football."
PSG president Nasser Al-Khelaifi confirmed the capital club have designs on the cup which currently resides in Real Madrid's trophy cabinet and has backed Luiz to make a big impact during the 2014-15 campaign.
The former Benfica defender has already won the continent's biggest prize, with Chelsea back in 2012.
"David Luiz will help us achieve our goal of winning the Champions League," he said.
"I am very happy with his arrival. I hired him for his many qualities, both as a man and as a footballer.
"David has an excellent team spirit and many other great qualities."