The Hollywood actor and director, 71, and artist Szaggars, 51, said ‘I do' at the posh Louis C. Jacob Hotel on the bank of the Elbe river before some 30 guests on Saturday afternoon.
"The ceremony was very important to them," protestant pastor Frank Engelbrecht, who officiated the marriage, told news agency AFP.
Redford speaks German, so the ceremony was conducted in the local language, Engelbrecht said.
His second wife comes from Hamburg where family members also still live. He has been known to secretly visit the city in the past to see Szaggar's family.
Sources told the paper that bride wore a champagne-coloured dress, and the groom donned a white suit.
The couple reportedly stayed at the hotel until Monday.
A second nuptial celebration is rumoured to be held in Mexico in September.
The pair met in the 1990s at one of Redford's Sundance Film Festival events, and Szaggars moved into Redford's Utah home in 1996, Hamburger Abendblatt reported.