|Date of birth||10 February 1979|
|Place of birth||Tallinn, Estonia|
|Height||1.82 m (5 ft 11 1⁄2 in)|
|1996–2000||FC Flora Tallinn||74||(26)|
|2003||→ FC Flora Tallinn (loan)||15||(11)|
|2004–2008||FC Flora Tallinn||51||(18)|
|2004||→ Enköpings SK (loan)||9||(4)|
|2005||→ Fredrikstad FK (loan)||6||(1)|
|2006||→ Gefle IF (loan)||26||(2)|
|2011–2012||JK Nõmme Kalju||63||(24)|
|2013–||Estonia (beach soccer)|
|* Senior club appearances and goals counted for the domestic league only.
Born in Tallinn, Viikmäe started his career with FC Flora Tallinn, and has since played for Tallinna Jalgpallikool, Tallinna Sadam, Vålerenga, Enköpings SK, Fredrikstad, Gefle IF and Jönköpings Södra IF. January 2010 he moved to Panegialios F.C., a third division team in Greece. He left the club in September because of salary problems. In January 2011 he joined JK Nõmme Kalju. On 9 October 2012, he scored the winning goal in a 1–0 victory against FC Kuressaare, which secured JK Nõmme Kalju's first ever title. After the match, Viikmäe announced his intention to retire at the end of the season. He scored in his last match on 5 November 2012.
During his national team career he has been capped 115 times and scored 15 goals. He made his debut on 26 January 1997 in a friendly against Lebanon, replacing Andres Oper in the second half. On 30 May 2006, at the age of 27 years and 109 days, Viikmäe became the youngest European footballer to reach 100 caps, which was beaten by German striker Lukas Podolski (27 years and 13 days) during Euro 2012. His testimonial match for the national team, as with all Estonians who are capped more than 100 times during their career, was held on 3 June 2013 against Belarus.
- Estonian Silverball: 2004
|1.||4 June 1998||Kadriorg Stadium, Tallinn, Estonia||Faroe Islands||5–0||Won||UEFA Euro 2000 qualifying|
|2.||6 March 1999||Antonis Papadopoulos Stadium, Larnaca, Cyprus||Azerbaijan||2–2||Draw||Friendly|
|3.||3 November 1999||Mohammed Bin Zayed Stadium, Abu Dhabi, UAE||Turkmenistan||1–1||Draw||Friendly|
|4.||19 March 2001||Cairo International Stadium, Cairo, Egypt||Egypt||3–3||Draw||Friendly|
|5.||9 May 2001||Kuressaare linnastaadion, Kuressaare, Estonia||Finland||1–1||Draw||Friendly|
|6.||10 November 2001||Nikos Goumas Stadium, Nea Filadelfeia, Greece||Greece||4–2||Lost||Friendly|
|7.||12 October 2002||A. Le Coq Arena, Tallinn, Estonia||New Zealand||3–2||Won||Friendly|
|8.||20 November 2002||A. Le Coq Arena, Tallinn, Estonia||Iceland||2–0||Won||Friendly|
|9.||7 June 2003||A. Le Coq Arena, Tallinn, Estonia||Andorra||2–0||Won||UEFA Euro 2004 qualifying|
|10.||28 April 2004||A. Le Coq Arena, Tallinn, Estonia||Albania||1–1||Draw||Friendly|
|11.||30 May 2004||A. Le Coq Arena, Tallinn, Estonia||Denmark||2–2||Draw||Friendly|
|12.||18 August 2004||Rheinpark Stadion, Vaduz, Liechtenstein||Liechtenstein||1–2||Won||2006 World Cup qualification|
|13.||4 September 2004||A. Le Coq Arena, Tallinn, Estonia||Luxembourg||4–0||Won||2006 World Cup qualification|
|14.||17 August 2005||A. Le Coq Arena, Tallinn, Estonia||Bosnia and Herzegovina||1–0||Won||Friendly|
|15.||6 June 2009||A. Le Coq Arena, Tallinn, Estonia||Equatorial Guinea||3–0||Won||Friendly|
|Correct as of 4 July 2017|
- "Kõik Eesti internatsionaalid" [All Estonian internationals] (in Estonian). Eesti Jalgpalli Liit. Retrieved 6 February 2012.
- Viikmäe kübaratrikist Levadiale: lihtsalt kukkus nii välja!(in Estonian)
- Kristen Viikmäe jätkab karjääri Nõmme Kaljus(in Estonian)
- "Ajaloolise värava löönud Viikmäe lõpetab karjääri" (in Estonian). Postimees. 9 October 2012. Retrieved 11 November 2012.
- "Viikmäe lõpetas karjääri väravaga, ees ootab lahkumismäng koondises" (in Estonian). Postimees. 5 November 2012. Retrieved 11 November 2012.
- "Liibanon – Eesti 2:0" (in Estonian). Jalgpallihaigla. Retrieved 11 November 2012.
- "BREAKING: Podolski youngest European to 100 caps". infostradalive.com. 17 June 2012. Retrieved 11 November 2012.
- "Eesti kohtub Valgevenega" (in Estonian). Estonian Football Association. 3 June 2013. Retrieved 3 June 2013.
- "Karjääri lõpetav Viikmäe hakkab Kalju noortetööjuhiks" (in Estonian). Postimees. 2 November 2012. Retrieved 11 November 2012.
- "Football PLAYER: Kristen Viikmäe". eu-football.info. Retrieved 4 July 2017.
- Kristen Viikmäe at National-Football-Teams.com