Born in Pontedera, Province of Pisa, Dainelli started his professional career at Empoli. He spent his early years on loan at Modena (Serie C1), Cavese (Serie C2) and Fidelis Andria (Serie C1).He was signed by Lecce in 2000 in a co-ownership deal and made his Serie A debut against Roma on 18 February 2001.

Brescia

After just one season at Lecce, he re-signed for EmpoliNEWS,www.legaseriea.it/c/document_library/get_file?uuid=6af3672f-fbed-4eaa-8921-03384562bbae&groupId=10192, Campagna trasferimenti, 28 June 2001, 30 December 2011, Lega Calcio, it, {{dead link|date=December 2016 |bot=InternetArchiveBot |fix-attempted=yes }} before moving to Brescia.Except for the first season which he just made five appearances and left on loan to Serie A rival Verona,NEWS,hellasverona.it/news.php?id=412, E’ UFFICIALE, DAL BRESCIA ARRIVA DARIO DAINELLI, 15 January 2002, 8 April 2010, Hellas Verona FC, it, he made 56 appearances more for Brescia.

Fiorentina

In July 2004, Dainelli signed for newly promoted team Fiorentina, in a co-ownership deal with Brescia. In January 2005, Fiorentina immediately bought all of the remain registration rights.Dainelli was the team captain after Christian RiganÃ² left the club in summer 2005,{{citation needed|date=June 2010}} a position which he hold until his transfer to Genoa.At the end of 2006â€“07 season, due to his contract expiring on summer, some rumor linked him with Juventus and other Italian clubs,{{citation needed|date=October 2009}} but on 9 June 2007, he finally signed a new four-year contract extension with Fiorentina.In summer 2009, ACF Fiorentina prepared to sell the captain by signing Cesare Natali in order to increase the depth of the bench. Alessandro Gamberini, Per KrÃ¸ldrup and Dainelli rotated at the starting pair of the central defender.

Genoa

After the signing of Felipe, on 12 January 2010 Dainelli was transferred to Genoa with whom he signed a contract which lasted until June 2013.NEWS,www.genoacfc.it/index.php?option=com_content&task=view&id=8785&Itemid=31, MERCATO: E’ FATTA PER DAINELLI AL GENOA, 12 January 2010, 12 January 2010, Genoa CFC, it,

Chievo

On 31 January 2012, the last day of 2011â€“12 winter transfer window, Dainelli moved to the fellow league club Chievo Verona on a loan deal.NEWS,www.chievoverona.it/en/news/dario-dainelli-joins-chievo-genoa, Dario Dainelli joins Chievo from Genoa, 31 January 2011, 2 February 2012, A.C. ChievoVerona, www.chievoverona.it, dead,www.chievoverona.it/en/news/dario-dainelli-joins-chievo-genoa," title="web.archive.org/web/20140116112934www.chievoverona.it/en/news/dario-dainelli-joins-chievo-genoa,">web.archive.org/web/20140116112934www.chievoverona.it/en/news/dario-dainelli-joins-chievo-genoa, 16 January 2014, He returned to Genoa after the loan deal expired at 30 June 2012 and then terminated his contract with Genoa. On 7 August 2012, he agreed a permanent deal with Chievo.

Livorno

On 16 July 2018, Dainelli signed with Livorno.NEWS, Livorno, arrivano Kozak e Dainelli,www.lasicilia.it/news/sport/175387/livorno-arrivano-kozak-e-dainelli.html, 16 July 2018, La Sicilia, 16 July 2018, it, On 13 May 2019, he announced his retirement.WEB,www.gazzetta.it/Calcio/Serie-A/Fiorentina/13-05-2019/dainelli-dice-basta-lascio-calcio-cambio-vita-fiorentina-livorno-3301583366659.shtml, Dainelli dice basta: “Lascio il calcio e cambio vita”, gazzetta.it, it,

International career

Dainelli played once for Italy U21 team, on 16 April 2002. a friendly 2â€“3 loss to France U21.He was also called up to 2002 UEFA European Under-21 Football Championship, but did not play.WEB, European U-21 Championship 2002 - Final Tournament Details,www.rsssf.org/tablese/eur-u21-2002det.html, www.rsssf.org, 9 November 2023, Dainelli made his debut for the Italy national team against Ecuador on 11 June 2005 a friendly match which ended in a 1â€“1 draw.WEB, Quanto ci mancherÃ la coppia Dainelli e Gamberini,www.ultimouomo.com/dainelli-gamberini/, L’Ultimo Uomo, 9 November 2023, it-IT, 14 September 2018, He was recalled by new Italian head coach Roberto Donadoni to play in Euro 2008 qualifying against Lithuania and France on 2 September 2006 and 6 September 2006, but did make an appearance.NEWS,www.gazzetta.it/Calcio/Nazionale/Primo_Piano/2006/08_Agosto/27/convocati.shtml, Cassano rivede l’azzurro, www.gazzetta.it, it, De Stefano, Gaetano, 27 August 2006, 9 November 2023,