Austria-born Radlinger – who stands at an imposing 6ft 6in – worked under head coach Daniel Stendel at Hannover and has now been tempted into English football by the Reds chief.
The 26-year-old’s arrival follows on from last week’s signing of former Chelsea custodian Bradley Collins, with the pair to battle it out for the No 1 jersey following Adam Davies’s departure to Championship rivals Stoke City.
On the new signing, co-chairman Paul Conway said: “This represents our fifth signing of the summer transfer window with more to come.
“Samuel has a long history with Daniel and extensive experience in his high pressing system at their previous club Hannover 96.”
The keeper started his career in his native Austria at hometown club SV Ried before joining Hannover in June 2011.
In eight years at the club, Radlinger made just five appearances for the first team, spending his early years with the club’s reserve side.
The keeper spent a loan spell with Rapid Vienna in the Austrian Bundesliga in 2013-14 and had a temporary stint with FC Nurnberg’s second team in the following season.
He joined Norwegian top-tier side SK Brann in January 2018, making 22 appearances.
Radlinger has represented Austria at every international level from Under-18 to Under-21 and was the first-choice goalkeeper at the 2011 FIFA Under-20 World Cup.
Rotherham United captain Will Vaulks is set to complete his move to Neil Warnock’s Cardiff City later today.
Vaulks, 25, agreed terms with the Bluebirds earlier this month and the deal is now expected to be finalised.
Unconfirmed reports have suggested that the fee will rise to £3.5m, with the Bluebirds paying £2.1m up front.
Vaulks’s former club Falkirk have a percentage sell-on fee inserted into deal and are entitled to an unspecified payment.
Bradford City’s marquee home friendly with Champions League winners Liverpool on Sunday, July 14 is on course to attract a near sell-out crowd.
Sales have passed the 20,000 mark and the club have now opened the TL Dallas Stand to home supporters.