Pioli, whose short reign as coach of Palermo ended last month before a Serie A ball had been kicked, inherits a side bottom of the league with one point from five matches.
"Stefano Pioli is from today the new coach of Bologna," the club said in a statement on their website hours after Bisoli's dismissal was announced.
"He has signed a two-year contract and will be presented to the press tomorrow [Wednesday]."
The 45-year-old Pioli, who has previously coached Salernitana, Modena, Parma, Grosseto, Piacenza and Sassuolo, led Chievo Verona to 11th place last season before replacing Delio Rossi at Palermo.
Earlier on Tuesday, the Rossoblu, who finished two places above the relegation zone last term under Alberto Malesani, dismissed Bisoli after four months in charge. Sunday's 2-0 loss at Udinese was their fourth defeat of the season.
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