The King Frederik IX bridge (Danish: Kong Frederik den 9's Bro; named for King Frederik IX of Denmark) is a combined road and railway bridge carrying the Danish national road 9 as well as Sydbanen and Lollandsbanen railway lines across the Guldborgsund strait between the islands of Falster and Lolland in Denmark.

The rail link is a part of the railway section of the Fugleflugtslinjen transport corridor between Copenhagen, Denmark and Hamburg, Germany.

There is a decision to widen the bridge with one more rail track and to fit electric overhead line, in connection with the Fehmarn Belt Tunnel.

In order to cut costs, there a tunnel company wanted to disallow bridge openings.

Two motors, one either side of the bridge, turn shafts passing through the centre of the pivot bearings.