|Date of birth||19 June 1986|
|Place of birth||Athens, Greece|
|Height||1.71 m (5 ft 7 1⁄2 in)|
|Playing position||Winger, Striker|
|2010||→ Olympiakos Volou (loan)||9||(2)|
|2012–2013||FK Khazar Lankaran||21||(6)|
|2015–2016||Ceahlăul Piatra Neamţ||9||(3)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 10 June 2018
Ethnikos Piraeus, PAS Giannina and Olympiakos Volou
In July 2008, Sialmas signed a two-year deal with Ethnikos which lasted for only one. Then, Giannina approached him and signed him, as PAS thought that he was an extremely talented striker. Giannina fans loved him, something that intrigued the Volos club and that led Olympiakos to borrow him for 6 months.
On the 30/5/11 Sialmas signed a three-year deal with AEK Athens on a free transfer keeping him at the club until 2014. Sialmas also chose the number 11 Jersey previously worn by former AEK player Demis Nikolaidis. His skills and movements reminded ΑΕΚ fans of the legendary Demis Nikolaidis and many of them compared the two. Sialmas scored two goals against Levadiakos and helped AEK to win 0-2. He was also given the MVP award.
In the summer of 2012 Sialmas signed for Azerbaijan Premier League side Khazar Lankaran on a one-year contract. Sialmas scored six goals in 24 games in all competitions for Khazar, as well as reaching the 2012–13 Azerbaijan Cup final. In the final the game went to penalties after finishing 0-0 after extra time, Sialmas took and missed the opening Khazar penalty, resulting in Neftchi Baku winning 5-3 on penalties. Sialmas was released at the end of his contract in the summer of 2013.
Ceahlăul Piatra Neamţ
In January 2015, Dimitris Sialmas decided to stay abroad, although he had offers from Greek Super League clubs to be repatriated. The Greek striker will continue his career in Ceahlăul Piatra Neamţ for the next six months, which struggling for remaining in the first division of the Romanian championship.
On 30 August 2017 he moved to Football League side Trikala. On 21 September 2017 he made his debut and scored his first goal, with a beautiful bicycle kick, in a 3-1 away win against Sparti for the Greek Cup. However, before the final whistle he was injured and one day later the medical diagnosis confirmed that he had suffered a cruciate rupture. He is expected to return in five months. On 13 May 2018, in the second game following his recovery from his injury, he came in as a substitute and scored with a stunning bicycle kick in a 1-0 home win against Aiginiakos.  One week later he scored with an amazing 30-yard shot in a 1-0 away win against Kallithea.
- "Dimitrios Sialmas and Vanderson Skarduelli are officially in "Khazar Lankaran")". lankaranfc.com. Archived from the original on 21 October 2013. Retrieved 27 September 2013.
- "Σιαλμάς και επίσημα στον Πλατανιά". sport24. Retrieved 12 December 2013.
- "Στη Ρουμανία ο Σιαλμάς". arenalarissa.gr. Archived from the original on 5 May 2015. Retrieved 23 January 2015.
- "Officiellt: Akropolis IF värvar Dimitrios Sialmas". fotbolltransfers.com. 29 March 2016. Retrieved 21 April 2016.
- Στην Παναχαϊκή ο Σιαλμάς, contra.gr, 23 August 2016 (in Greek)
- "Στα Τρίκαλα ο Σιαλμάς!" (in Greek). Retrieved 2017-08-30.
- "Νίκη για τα Τρίκαλα!" (in Greek). Retrieved 2017-09-21.
- "Σοκ με Σιαλμά!" (in Greek). Retrieved 2017-09-22.
- "Κοντά στον τίτλο ο ΟΦΗ, νίκησε με ανατροπή στην Άρτα". www.sport24.gr. 13 May 2018.
- "Σώθηκε ο Εργοτέλης, όλα ανοιχτά για τρεις...!" (in Greek). Retrieved 2018-05-20.