Tomi Metsäketo started his career in the late 1980s as a boy soloist at the Savonlinna Opera Festival and the Finnish National Opera. In autumn 1998, he was selected for the European Union Opera program including master classes, lectures and concerts in Baden-Baden and Paris. His studies have also included singing courses in Rome under the direction of Tina Scapin.
Metsäketo has appeared in numerous musicals, debuting in the role Archibal Craven in The Secret Garden in 1996 at Aleksanteri Theater in Helsinki. He has peformed, for example, in The Sound of Music (Rolf) at the Helsinki City Theater in 1998, Les Misérables (Marius) at the Helsinki City Theater in 2000, Calypso (Odysseus) at the Hartwall Arena in Helsinki in 2002, Elisabeth (Franz Josef) at the Turku City Theater in 2005–2006, Titanic (Barret) in Seinäjoki City Theater in 2008–2009, and Les Misérables (Marius) in Åbo Svenska Teater in 2011–2012 and Tampere Theater in 2013–2014.
In 2002, Metsäketo released his debut album Primo, which went gold and earned him an Emma award nomination for 2002 debut album and male artist of the year. In October 2004, Metsäketo's second album Tummaa samettia ("black velvet") was released, which went platinum. The album was also nominated for Emma award as the best-selling album of 2004.
In 2005, Metsäketo performed, for example, Love Is A Song on Walt Disney's Bambi cartoon dubbed in Finnish. The same year, Metsäketo and Laura Bono, the winner of the Sanremo songs contest, recorded the duet Oggi Ti Amo.
In 2006, Metsäketo competed in Finland's Eurovision song contest with the song Eternamente Maria achieving second place after Lordi. Metsäketo's third full-length album, Eternamente, was released in May 2006. A Christmas edition of the album was released later that year.
In 2007 Metsäketo toured with Johanna Kurkela and in 2008 Laura Voutilainen, two Finnish female vocalists. Metsäketo's fourth album, Roma, was released in 2008. Metsäketo has also acted as member of the jury in the Finnish television program Suomen paras kuoro, "the best Finnish choir".
In 2010, Metsäketo released his first Christmas album, Kuului laulu enkelten, which went platinum and was chosen as the Christmas album of the month by Finnish radio journalists. Metsäketo has also done a Christmas tours with Laura Voutilainen and with Saara Aalto.
In the spring of 2011, Metsäketo released the Tomi Metsäketo – All the best – 10th anniversary album.
Over the years, Metsäketo has performed on several tours of Tuliset tenorit together with Finnish tenors Jyrki Anttila and Pentti Hietanen, and in the Sopraanot Metsäkedolla concert series together with Finnish sopranos Maria Lund, Päivi Pylvänäinen and Maija Ruuskanen. The tours included, for example, Wieniläisverta (2016), Sinun omasi (2017), Tangon 7 veljestä (2018–2019), Mambo Italiano (2019) and Besame Mucho (2020–2021).