"During 2015, 50,628 Croatian citizens settled in Germany, and 12,918 left. At the end of 2015, there were 297,895 Croatian citizens living in Germany," the office's spokesman Gunter Brueckner said on Monday.
A rising number of Croatians have been emigrating to Germany since Croatia joined the European Union in mid-2013.
In 2014, 44,260 Croatians settled in Germany, and 17,327 left that western European country.
Precise data about immigrants broken down by their citizenship will be released later this week.
"The year 2015 was characterised by unusually high immigration of foreigners to Germany. Based on provisional results of a flash estimation of migration statistics, the Federal Statistical Office reports that the arrival of just under 2 million foreign people was registered by the end of 2015. At the same time, roughly 860,000 foreigners departed from Germany. Consequently, net migration of foreign people amounted to 1.14 million. This is the highest net immigration of foreigners ever recorded in the history of the Federal Republic of Germany," the Office said on its web site.