Social Democratic Party (SDE) MP Raimond Kaljulaid has also joined the party's grouping at the Tallinn City Government chamber.
Kaljulaid recently joined SDE having been an independent since leaving the Centre Party in May. He is also tipped by some as potential leader of the city government SDE faction.
The decision was made on Thursday to admit Kaljulaid to the city government, BNS reports.
Kaljulaid also highlighted his shared vision with the party on a number of substantive issues related to Tallinn's development, including road construction, public transport organization, municipal development, education and healthcare policies, as well as social support and services, BNS reports.
"We all deem strong contribution to developing a convenient modern public transport the right thing to do," Kaljulaid said on Thursday.
"We also deem it right that all those in need, particularly the elderly, should be supported through efficient and accessible social services. We share a common concern that in many city districts, including the North Tallinn district, important investments have been postponed, and developments which hold key importance in terms of the city's development are moving forward too slowly," Kaljulaid continued.
Members of the SDE group in the Tallinn city council also include Anastassia Kovalenko, Anto Liivat, Kadri Kõusaar, Karl-Martin Sinijärv, Helve Särgava, Kadi Pärnits, Annela Ojaste, Siim Tuisk and Rainer Vakra.
Kaljulaid had previously been a district elder in North Tallinn, when he was in the Centre Party.
Estonian MPs can also sit on the city council simultaneously.
Editor: Andrew Whyte