On completion of his SASI program in 2000, Iain joined hometown
NSL club
Adelaide City. After just three appearances off the bench in 2000–01, he broke into the Adelaide first team the following season, making 52 appearances in two years before moving to
Sydney Olympic in 2003. He also earned a call up to the
Australian Under-23 side for a friendly against
Spain, but it would be the only one. Domestically, his move was positive, becoming a key figure for Olympic, playing all-but-one matches of the 2003–04 season.
Scotland Following the collapse of the NSL after that season, Fyfe went overseas and trialled at various clubs, including
Scottish Premier League side
Hibernian, before signing for
Hamilton Academical in the
Scottish Second Division. There he played alongside fellow Australians,
David Carney as well as childhood friend and former Adelaide City teammate
Scott Tunbridge. Fyfe struggled to break into the Hamilton first team, making only fifteen appearances before being released in early 2005.
Sydney FC Partnered next to first
Mark Rudan and later
Jacob Timpano, Fyfe was in the Sydney first XI for much of the
A-League season. However, he was dropped to the bench for the penultimate round due to inconsistent form. Several strong performances from Rudan kept him there, making only one start and three appearances off the bench in the club's last five games, although a missed match was through suspension. In the A-League grand final, Fyfe played an important role in defending Sydney's 1–0 lead over the
Central Coast Mariners, having replaced injured Mark Rudan with 20 minutes remaining. In the
2006–07 season, Fyfe was shifted to a wide defensive role by new coach
Terry Butcher, who opted to play
Mark Milligan in midfield rather than his usual right back position. The impact of the move was immediately apparent with Fyfe, goal-less in the previous season, scoring the winning goal against Central Coast in the opening round and netting again in the 3–2 loss to
Melbourne Victory a week later. He went on to play every match of the season up until Sydney's semi-final exit. Strong performances led to another call up to the national team, included in the A-League-based Australian side for the
2007 Asian Cup qualifier against
Kuwait on 16 August 2006, but again did not make an appearance. During the
Pan-Pacific Championship Iain played his 100th competitive game against
Major League Soccer Glamour team
Los Angeles Galaxy. Sydney went on to lose the match 2–1, with Sydney's goal coming from
Brendan Renaud. He was Sydney's most capped player, and most consistent, only missing 3 competitive matches, in the 3 years Sydney have played in the
A-League.
Adelaide United On 24 November 2008, it was announced in November that Iain had signed a contract with
Adelaide United commencing April 2009; this brings Fyfe back to
Adelaide where he began his career after 5 years playing in Sydney and
Scotland. Starting all the games in the opening of his
first season back at Adelaide, Fyfe's first goal allowed his club to equalise against
Wellington Phoenix in round five. He scored his second goal for Adelaide in a 1–1 draw against
Central Coast Mariners in Round 2 of the 2010–11 season. On 14 January 2011, it was announced that Iain would be joining
K-league club
Busan I'Park FC. His farewell game for Adelaide was meant to be on 29 January 2011 against
Central Coast Mariners at
Hindmarsh Stadium, but due to a hamstring injury his last game was on 21 January 2011 against
North Queensland Fury when they won 8–1.
Busan I'Park In January 2011, Fyfe joined
South Korean club
Busan I'Park. Fyfe made his first start and debut for Busan I'Park in their 2–1 away loss to
Jeju United in the first week of the
2011 K-League season.
Return to Adelaide United On 29 February 2012, it was announced that Fyfe had signed a one-year undisclosed contract with club
Adelaide United after his contract with South Korea
K-League club
Busan I'Park.
Mes Kerman He was linked to a move to the
Iran Pro League in summer 2013. On 2 August 2013,
Mes Kerman announced that Fyfe will be joined to the team after passing medical test. He officially joined to the team on 10 August and signed a two years contract. He made his debut in a 1–0 loss to
Saipa.
Newcastle Jets In November 2016, Fyfe signed a short-term deal to return to the
A-League with
Newcastle Jets as an injury replacement for
Daniel Mullen, joining from South Australian club
Campbelltown City. ==International career==