Taken together, the entire project is known as the Southern Gas Corridor which is costing some USD 40 billion to build and was inaugurated in late May.
Erdogan inaugurated the pipeline at a ceremony attended by leaders including Azerbaijan's President Ilham Aliyev, Ukrainian President Petro Poroshenko and Serbian President Aleksandar Vucic in the Turkish region of Eskisehir southeast of Istanbul, one of 20 provinces in Turkey the pipeline passes through.
"TANAP is the latest fruit of a shared vision," Erdogan said at the opening ceremony, describing the pipeline as part of a new "energy Silk Road".
The leaders then watched as the final section of the pipeline was lifted into place and then turned a wheel to allow the gas to flow.
The Turkish leader is battling a tightly fought contest for presidential and parliamentary elections, boasting at rallies nationwide of his ability to deliver on big projects.
During Erdogan's over 15 years in power, first as premier and then as president, Turkey has seen a massive revamp of infrastructure with new high speed rail lines, roads and the Bosphorus in Istanbul spanned by one new bridge and two undersea tunnels.
He is touting a daring new plan to build a Panama-style shipping canal in Istanbul as boasting that a brand new airport for the city is near complete.
The 1,850 kilometre TANAP will initially pump 2 billion cubic metres of gas annually for use in Turkey, rising to 6 billion. By 2019 another 10 billion cubic metres of gas will be delivered into Greece for use in Europe.
A majority 58 per cent in the TANAP project is owned by Azerbaijan through state energy firm SOCAR. Turkish state energy firm Botas and British energy giant BP have minority stakes of 30 per cent and 12 per cent respectively.
But rights activists have slammed the Southern Gas Corridor projects, saying its Western backers are turning a blind eye to rights violations in Azerbaijan under the rule of Aliyev.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)