"Croatia's path to the European Union will not be easy and without obstacles, but I approach my duties with optimism and am confident of ultimate success," Drobnjak told Hina in an interview.
Earlier on Wednesday, Prime Minister Ivo Sanader and leaders of Croatian parliamentary parties agreed to appoint Drobnjak chief negotiator with the EU.
Drobnjak said he was travelling to Zagreb next week to begin preparations for membership talks with the EU, which are scheduled to open on March 17.
"Croatia has shown that it has the necessary political and professional knowledge, capabilities and strength to draw closer to the European Union at an accelerated rate and to successfully cope with all the challenges of that process, so there is no reason for that not to continue in the future," he said.
Drobnjak thanked the Croatian government for its trust in him and the prime minister for his words of praise for him.
"It is a great credit to me personally and to Croatian professional diplomats, but also a huge responsibility," he added.
Sanader said that Drobnjak was a great professional, one of the best Croatian ambassadors, and that he had excellent knowledge of European institutions.
Drobnjak also thanked all the parliamentary parties for their "consensual support".
Drobnjak said that the membership talks could be brought to a successful close "only through joint efforts and with the full involvement of all segments of society".
Drobnjak has great experience in relations with the European Union. He served as ambassador to the EU in Brussels from 2000 to 2003. He was a member of the Croatian negotiating team in talks on the Stabilisation and Association Agreement, and was also involved in the preparation of candidacy for EU membership.
Drobnjak joined the Croatian diplomatic service in 1992. He served as assistant foreign minister for multilateral affairs from 1997 to 2000, and national coordinator of the Stability Pact for Southeast Europe.
Drobnjak, aged 48, has a law degree. He is married and has one child.