Barry Nicholson was born in Dumfries on 24 August 1978.
As a boy Nicholson was a supporter who watched home town club Queen of the South with his father. From playing youth football in Dumfries he then joined Rangers as a youth player. Limited appearances in Rangers' first team saw make just 8 league appearances from 1995 to 2000. His debut was a 4-0 win at Dundee on 27 January 1999; his final appearance match was a 6-2 home win over Motherwell 18 March 2000. He scored once for Rangers in a Champions League qualifier first leg against FC Haka on 28 July 1999, which Rangers won 4-1.
Nicholson joined Dunfermline Athletic under the helm of Jimmy Calderwood and was first team regular in what was the Pars most successful period for a considerable period of time 2002/03 in Scottish football saw them finish 5th.
His debut was a 3-0 defeat at Dundee on 5 August 2000, His first Pars goal came in a 2-1 League Cup defeat to St Mirren on 31 October 2000, Nicholson’s first league goal came in his next match four days later in a 2-0 win at St Johnstone. His first season saw him score 3 goals in 36 appearances.
Nicholson’s first brace came in his opening match of the 2001/02 season with a 5-2 win over Motherwell on 28 July 2001 and scored 7 goals in 37 matches.
The 2003/04 season saw Nicholson net 9 goals in all competitions including 3 in 3 matches with victories over Inverness CT, Motherwell and a 2-1 win at Celtic on 2 May 2004. Dunfermline did even better finishing in fourth place as well as reaching the 2004 Scottish Cup Final, which also saw them qualify for a UEFA competition for the first time since 1970. Nicholson played in the Final but Celtic won 3-1.
He made 174 league appearances and 23 goals for Dunfermline. Nicholson netted on his final match which ended in a 4-1 home defeat to Hibs on 19 March 2005.
Nicholson's performances at East End Park saw him signed by Aberdeen for a fee of £250,000 in July 2005 and re-joined former boss Calderwood who had since moved to Pittodrie. He scored on debut with a 1-1 draw at Dundee United on 30 July 2005
The move paid dividends as his strong performances towards the end of the 2006/07 season saw him score vital goals. The most notable of these goals was the last minute equaliser against Hearts and was then sent off, which all but clinched third place for Aberdeen.
In season 2006/07, the club finished in third place in the league and thus qualified for the 2007/08 UEFA Cup. Nicholson also scored his first hat-trick with a 4-1 victory over Inverness CT in the League Cup on 31 October 2007 with two of these goals being penalties.
After 13 goals and 102 matches for Aberdeen, Nicholson signed a two year contract with an option of a third year on a free transfer for Preston on 30 June 2008.
Nicholson scored his first goal for Preston in a 2–0 pre-season friendly away to Chorley. His made his Lilywhite debut in a 2-1 win at Ipswich on 9 August. Nicholson shored in his first two leagues matches at Deepdale with a 2-0 win against Crystal Palace on 16 August and a 2-1 victory over Charlton a fortnight later. He made 39 league appearances and 3 goals in 2008/09 as well as the two play-off matches against Sheffield United.
On 22 August 2009 Nicholson sustained a suspected broken leg in the Championship game versus Peterborough. Nicholson returned from injury for the final game of the 2009/10 season only to limp off the field within 15 minutes suffering from an injury to the same leg in the 4-1 defeat at Reading.
Nicholson returned to the side in January 2011 playing regularly for the remainder of the season, scoring a goal on 3 consecutive matches in the following month.
Nicholson netted twice in 30 games during 2011/12, his final match was a 1-0 defeat at Bournemouth on 5 May 2012. After scoring 9 goals in 93 league matches for PNE he was released by Preston at the end of the 2011/12 season.
Nicholson signed for Fleetwood Town for the 2012/13 season, his debut was a 1-0 home defeat to Nottingham Forest in the League Cup on 13 August. Nicholson scored both his goals for Fleetwood away from Highbury in a 4-0 win at Morecambe on 8 September 2012 and a 2-2 draw at Exeter on 10 November. He made 30 appearances for the Cod Army, with his final match being a 2- 1 defeat at Rotherham on 13 April 2013.
He then moved to Kilmarnock in August 2013 on a short term contract. On 24 August 2014, he scored his first goal for the club on his home debut in a 2–1 defeat against Hibernian. His final goal came in the next home match in a 2-1 defeat against Inverness CT. In January 2014, Nicholson's contract was extended until the end of the season. He made 23 league appearances for Kilmarnock, the last was a 1-0 win at Hibernian on 10 May 2013.
At the end of the 2013/14 season, Nicholson retired from playing and took charge of the new development squad at Fleetwood Town.
Nicholson has won three caps for Scotland, the first being in the friendly 1-1 draw with Poland on 25 April 2001. His only World Cup qualifier was a 2-1 home win over Latvia on 6 October 2001, whilst the last one was in the 4-1 home friendly defeat to Sweden on 17 November 2004.