Christian leaders spoke at the ceremonial opening and the City of
Duisburg Philharmonic Orchestra played as well as Turkish bands.
Police, who estimate that some 6,000 people attended Sunday's ceremony, said there were no protests.
In an inaugural speech, the premier of North Rhine Westphalia Juergen Ruettgers, affirmed the right of 3.3 million Muslims in Germany to build mosques as big as they liked.
"We need more mosques in this country, not in inner courtyards,
but visible and recognizable ones," he said.
Glass windows, no loudspeakers
The opening of the mosque could not have been more different from the controversy surrounding a planned one in nearby Cologne. In that city, some civic leaders have charged that a planned mosque is "too big." The city witnessed violent rioting last month as far rightists vainly attempted to hold an anti-Islam rally.
Officials say ethnic Turkish Muslims form a major group in gritty, working-class Duisburg, an old coal and steel town, as opposed to their affluent, middle-class counterparts in Cologne, 55 kilometers away.
In the Duisburg suburb of Marxloh where the mosque was built, Muslims make up about one-third of the 18,000 residents.
The designers of the 7.5-million-euro ($9.4-million) complex forestalled German criticisms by including plate-glass windows to make the mosque's inner workings more visible.
There will also be no muezzin calling to prayer by loudspeaker from the Duisburg mosque's 34-metre minaret, a practice that some anti-mosque groups elsewhere have seized on.
The state government and the European Union pumped in 3 million euros in subsidies for the complex, which includes a community centre, café and the mosque itself capped with several Ottoman-style domes.
Another 4 million euros was contributed by Muslim faithful in an
international fund raising drive.