The Reds have been on the lookout for a new mentor since interim boss Michael Valkanis announced earlier this month that he would return to his previous role as assistant coach.
While the likes of ex-Melbourne Victory coach Ernie Merrick and ex-Adelaide United assistant Phil Stubbins were heavily linked with the job, Gombau got the nod and will take up the reins at Hindmarsh Stadium in mid-July.
"I want to come to Adelaide because Australia has one of the most successful leagues in Asia at this moment and I want to enjoy this experience in the A-League because I think football in Australia is growing and it would be a pleasure for me to come to this club," Gombau said.
"I see it as a very good chance to grow in my coaching and I hope me and the club and that together we can make something nice by becoming champions in the A-League."
A qualified UEFA Pro Licence coach, Gombau will bring with him to Adelaide his current assistant Pau Marti to work alongside Valkanis.
"What we looked for in a coach was the ability to implement a football philosophy which is first and foremost successful," Adelaide United General Manager of Football Operations Michael Petrillo said.
'The by-products of the philosophy also need to produce a style that is entertaining and relevant to the modern game – a style that the players will understand and embrace as theirs.
"Josep has a wealth of experience within what has arguably been the best club in world football for the last decade.
'What is more important is that he has been able to successfully implement his own version of the football philosophy, methodology and developmental pathways at work at FC Barcelona as a Senior Coach of Kitchee in Hong Kong."
Adelaide was quick to announce Gombau's signing after he spilled the beans on talks between the parties a day earlier.
Speaking to TVB in China on Monday, Gombau revealed negotiations with Reds was at an advanced stage.
"There are some details to go through, but I think we could finish the job in one or two days," the 36-year-old said.
The former technical director of FCB Escola, a youth football academy affiliated to FC Barcelona, Gombau took over the reins at Hong Kong side Kitchee in 2009 and won back-to-back league titles in 2011 and 2012.
"I thank all the fans supporting me and Kitchee FC. Kitchee FC have done well, and your help is important," Gombau said.
"Kitchee FC still faces some challenges.
"I will still focus on my job and lead the team. I won't leave until the mission is over. [Then] I will officially say goodbye to everyone."
Hong Kong's league season ends next weekend while Kitchee is in the final of the Hong Kong Fa Cup on Saturday 11 May.