This result leaves Juventus in sixth place, seven points behind Serie A leaders Atalanta, though the outcome could have been more disappointing as Bologna seemed poised for victory at the Allianz Stadium.
Dan Ndoye opened the scoring for the visitors with a skillful finish from a narrow angle after 30 minutes, and Tommaso Pobega extended their lead seven minutes into the second half.
Juventus finally found their rhythm when Teun Koopmeiners netted a goal ten minutes later, but despite their relentless efforts, it appeared they were on the verge of suffering their first league defeat of the season.
As the match neared its conclusion, Mbangula, who had come on as a substitute, received a pass at the edge of the Bologna penalty area and skillfully placed his shot past goalkeeper Lukasz Skorupski. In an earlier match, Genoa and Torino ended in a goalless draw in a mid-table encounter. AS Roma is set to face Lecce in the late game on Saturday.