Fien, 34, has chosen to continue his involvement in rugby league through a Captain Coach role with the Thirroul Butchers in the local Illawarra Coal League next season as well as continuing to develop his financial servicing business and expertise.
"I feel really fortunate to have had the career and opportunities that rugby league has presented me with," said Fien.
"I am extremely grateful to everyone who has helped me along the way, from the start that the Cowboys gave me, the opportunity to cement a place in first grade at the Warriors and the opportunity be a part of the famous Dragons Red V and win a Premiership.
"Whilst I believe that I could have played on at the NRL level, the timing is right for me to step back from the NRL.
"The Dragons have recruited really well for next season, they are in good shape and I am really pleased to be able to stay involved in the game I love and the area through the Thirroul Butchers."
Fien indicated that the decision to retire from the NRL was tough but made easier by the fact that he has been preparing for life after football for some time and had a few options.
"It is a bit sad that it is all drawing to an end but I have been preparing for life after footy for a while now," said Fien.
"I started my invoice financing business FIFO Capital 18 months ago and I am completing a Diploma of Mortgage Broking through the mentorship of Corporate Finance Group in Wollongong.
"I will be able to continue to build and work on these two businesses and I am excited about this.
"The opportunity with Thirroul means that I can continue my association with rugby league and also give back to the sport with the hope of also maintaining a close association with the Dragons.
"I always thought that I would like to get into coaching one day so this is a great start and it will also enable me to work outside of rugby league as well."
The Mt Isa Brothers junior has played 272 first-grade games to date in a career which saw him debut for the North Queensland Cowboys in 2000 and later join the New Zealand Warriors in 2005.
The versatile play-maker joined the Dragons ranks midway through the 2009 campaign and made his Club debut that season in round 18 against the Manly-Sea Eagles at WIN Stadium, Wollongong.
The 2012 NRL All-Star representative has won many honours over his 14-season career including a Premiership (2010) and World Club Challenge (2011) with the Dragons.
Furthermore, Fien has been capped on 22 occasions for the New Zealand Kiwis and won both the World Cup (2008) and Four Nations (2010) with his country as well as representing the Queensland Maroons at State of Origin level (2001).
I have fantastic memories throughout my career and standing there with my teammates celebrating our Premiership win on grand-final day is up there, said Fien.
Holding that Premiership trophy is something that I will always remembers and I am thankful to be a part of such a great Club.
I was fortunate enough to be part of a special New Zealand team who won both the World Cup as well as the Four Nations and they too are tremendous memories I can reflect on someday.
Dragons CEO Peter Doust has praised Fien on a remarkable career which has seen the player accomplish everything in the game.
Nathan has had a remarkable career that has seen him play at all levels of the game across multiple clubs and representative teams as well as lifting every available trophy in the game, said Doust.
Playing 14 years in the NRL is to be respected and characterises his capabilities and commitment.
"Nathan is to be congratulated on both this achievement and for the way he has carried himself on and off the field during this time.
Nathan has been a significant contributor to our club as well as the game of rugby league and we are pleased that he has the opportunity to continue his involvement in the game and in our region through the Illawarra Coal Cup.
"On behalf of everyone at the Dragons I thank Nathan for his services and wish him well for his future with his business and family.
Dragons Head Coach Steve Price similarly echoed these sentiments.
Nathan is an outstanding character who has given his all for this Club during his time here, said Price.
He has been a reliable player who has fitted into whatever role the team has needed him for and he has been a great influence on our younger players.
The entire playing squad wishes him all the best and we know he will be successful in the next step of his footballing career at the Butchers.
Click to read the Dragons NRL Line-Up for Round 23