Playing for the first time since missing out on qualification for the 2018 World Cup, Martin O'Neill's side handed debuts to Aston Villa striker Scott Hogan and West Ham United's Declan Rice, while captain Seamus Coleman played his first international since returning from a double leg fracture.
The opening stages passed by without incident but Irish goalkeeper Colin Doyle had to be alert to keep out a long-range effort before the quarter-hour mark.
Republic of Ireland have a glorious opportunity to take the lead soon afterwards when Hogan raced clear on goal but after rounding the goalkeeper, the debutant fired the ball into the side-netting.
However, Turkey continued to have the better of the play and Ireland were fortunate not to concede when Gokhan Gonul's cross caused confusion between Shane Duffy and Doyle before going away from danger.
Soon after the restart, Turkey got the goal that their play deserved when the ball was delivered from the byline for Topal, who made no mistake from inside of the penalty area.
The Irish had the chance to draw level four minutes later when Jeff Hendrick's free kick found the head of Duffy in the penalty area, but the Brighton & Hove Albion man put his effort wide of the left upright.
Doyle was called into action again in the 67th minute following a surging solo run by AC Milan's Hakan Calhanoglu, who went in alone and let fly, forcing a save out of the visiting goalkeeper.
Half-chances fell to Rice and Daryl Horgan in the closing stages, though neither of them were able to find the target as Turkey held on for a victory that was far more comfortable than the scoreline suggests.
TURKEY (4-2-3-1): Babacan; Gonul, Aziz (Ayhan 82'), Soyuncu, Ali Kaldirim; Yokuslu, Topal; Yazici (Potuk 87'), Akbaba (Malli 69'), Calhanoglu (Kahveci 80'); Tosun (Unal 64')
REPUBLIC OF IRELAND (5-3-2): Doyle; Coleman (Doherty 63'), Long, Duffy, Rice, McClean; Hourihane (Clark 69'), Browne (Meyler 68'), Hendrick (Judge 80'); Maguire (Long 62'), Hogan (Horgan 75')