The surge made Turkey one of the world's fastest expanding economies in the three months to September, outstripping bigger emerging markets China and India and eclipsing Romania, the European Union's fastest-growing economy.
But analysts warned that its growth -- which relies on private consumption and government stimulus -- is uneven and likely to cool.
President Tayyip Erdogan is pushing banks to lend more to boost consumption and the economy. Investors want to see higher household savings and structural reform, rather than borrowing and spending. "A stonking number -- and even though well signposted that it would be double digit, over 11 percent was an incredible number," said Tim Ash of BlueBay Asset Management. "The problem still is the quality of growth ... This does not seem sustainable."
The service sector expanded by 20.7 percent while construction and industry also grew by double digits, the data showed. Overall, the economy's expansion beat a forecast of 10 percent growth in a Reuters poll. It grew 1.2 percent from the previous quarter.
Following last year's failed coup, which led to a 0.8 percent contraction in the third quarter, the government ramped up its stimulus measures, including changes to tax regulation.
Its Credit Guarantee Fund, which backs loans to small and medium-sized enterprises that could not otherwise get credit, was increased more than tenfold to 250 billion lira ($65.24 billion) in March.
Following the release of the data, Development Minister Lutfi Elvan forecast 2017 growth would be 6 to 7 percent.
RATE HIKE?
There was some speculation among analysts that the strong growth figures, coupled with recent high inflation, could prompt Turkey's central bank to increase interest rates when its monetary policy committee (MPC) meets on Thursday.
Erdogan, a self-described "enemy" of interest rates, wants to see low borrowing costs to encourage consumption. The central bank's reluctance to increase rates, even in the face of double-digit rises in inflation, has reinforced perceptions that the bank is under political pressure.
"The annual rate of growth is likely to slow sharply in the coming quarters. Even so, today's GDP data, coming alongside November's jump in inflation, mean a rate hike at Thursday's MPC meeting now looks highly likely," said William Jackson of Capital Economics in London.
Inflation hit its highest in 14 years last month, surging nearly 13 percent as transport and food costs spiked.
Second-quarter growth was revised up to 5.4 percent from an initially reported 5.1 percent, while first-quarter growth was also slightly revised up, to 5.3 percent.
Separate data on Monday showed that the current account deficit narrowed to $3.827 billion in October, less than a Reuters forecast of a $4.1 billion deficit.