"We will be in the operation and we will be at the table," Erdogan said in a televised speech. "Our brothers are there and our relatives are there. It is out of the question that we are not involved."
The build-up for the offensive to retake Mosul from Islamic State (IS) jihadists, who have held Iraq's second city since June 2014, was marked by a bitter squabble between Ankara and Baghdad over the planning.
But Erdogan had indicated that the issue was discussed in talks in the United States over the weekend between Turkish chief of staff General Hulusi Akar and US counterpart Joseph Dunford.
Turkey had raised concerns over the possible involvement of Iraqi Shiite and anti-Ankara Kurdish militia in the offensive, while Baghdad had lashed out at the presence of a contingent of Turkish troops in Bashiqa, north of Mosul.
But Erdogan said the Turkish troops -- whose task is ostensibly to train Iraqi fighters to retake the city -- were in Bashiqa to stay.
"No-one should expect us to leave Bashiqa. We are there and have made all kinds of operations against Daesh (IS)."
- 'Serious problems' -
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Last week, Erdogan had warned Turkey would consider a "B" and "C" plan if its concerns were not addressed, without elaborating on the nature of the alternatives.
In a sign Ankara was trying to lower the temperature with Baghdad, Deputy Prime Minister Numan Kurtulmus said that a top-level Turkish delegation led by foreign ministry undersecretary Umit Yalcin was on its way to the Iraqi capital for talks.
With some three million Syrians and Iraqis already in Turkey, Kurtulmus warned of the risk of a new influx of refugees if the operation hits trouble.
"If Mosul goes wrong, if people are forced to flee, where will they go? Presumably they won't go to Washington. They will flee to Turkey," he said during a press conference in Ankara.
"That's why we say the Mosul operation must be done properly," he added.
Speaking after a cabinet meeting, he reaffirmed Turkey's insistence that Mosul must retain its identity as a Sunni Arab majority city once IS is ousted.
"Changing the sectarian demographic balance of Mosul will risk leading to serious problems," he said, saying powers needed to make sure the operation does not turn into a sectarian conflict.
He said 3,000 fighters trained by Turkey were taking part in the operation. Erdogan said on Friday that there were nearly 700 Turkish soldiers in Bashiqa.