Paris St Germain midfielder Motta has collected 13 caps but had not been included by Prandelli since last year's European Championships, while Sampdoria striker Gabbiadini returns to the fold after earning his only senior cap against England last August.
Brazilian-Italian Motta has made three league appearances for the Ligue 1 champions this season and former Juventus player Gabbiadini represented Italy's Under-21 side at the summer Championships in Israel - in which the Azzurri finished as runners-up to Spain.
AC Milan duo Mario Balotelli and Riccardo Montolivo and Southampton striker Pablo Osvaldo are all suspended for Friday's meeting with Bulgaria in Palermo but are available for selection in a clash with the Czech Republic at the Juventus Stadium in Turin on September 10.
Milan full-back Ignazio Abate missed a friendly defeat to Argentina earlier this month through injury but is recalled while Napoli striker Lorenzo Insigne hopes to add to his solitary goal for the senior side.
Italy currently lead Bulgaria by four points in Group B - with the Czechs a further point behind - meaning that, with only four games remaining, Prandelli's men could secure their place at the Brazil finals with two wins from the international weekend.