President Recep Tayyip Erdogan said the offer would be presented by Foreign Minister Mevlut Cavusoglu during Syria crisis talks in the Swiss city of Lausanne.
Cavusoglu "will present a proposal to coalition forces in Lausanne," Erdogan said in a televised speech.
"We are ready to fight there against Daesh and other terror groups," he added, using an Arabic acronym for the IS group.
The Turkish president on Friday warned that Ankara would have to resort to a "plan B" if its proposal to join the Mosul offensive was turned down, without saying what that could mean.
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Ankara is worried the offensive could be led by Shiite militia and also include Kurdish militia it vehemently opposes.
Turkey and Iraq are also at loggerheads over the presence of Turkish troops in Basiqa camp near Mosul.
Although Ankara says they are there to train local fighters planning to take part in the operation, the Iraqi parliament has labelled them an "occupying force".
"Nobody should talk about our base in Basiqa," Erdogan said on Saturday.
"That base will remain there because Basiqa is... an insurance against possible terror attacks targeting Turkey."