Leading 3-1 from the quarter-final first leg, Unai Emery’s team swatted aside Bologna with a 4-0 victory at Villa Park.
Forest, 12 spots below fourth-placed Villa in the Premier League, defeated 10-man Porto 1-0 in Nottingham to secure a 2-1 aggregate success.
Villa are into their second European semi-final under Emery after making the last four in the Conference League in 2024.
Europa League specialist Emery has won the tournament four times, three with Sevilla and one at Villarreal, and also finished as a runner-up with Arsenal.
Ollie Watkins had scored twice in the first leg in Italy and the England striker tormented Bologna again in the 16th minute.
It was an eye-catching goal as Villa’s flowing 14-pass move climaxed with Morgan Rogers setting up Watkins for a tap-in from six yards.
Watkins’ 100th goal for Villa made him the club’s top scorer in European competitions with 10, overtaking Peter Withe and John McGinn.
Villa missed a 25th minute penalty after Martin Vitik handled a header from Rogers, whose spot-kick was saved by Federico Ravaglia.
But it was only a temporary reprieve for Bologna as Emiliano Buendia struck with a fierce blast in the 26th minute.
Rogers made up for his penalty miss in the 39th minute, netting for the first time in 12 games with a drive that beat Ravaglia at his near post.
Ezri Konsa’s 89th-minute volley capped Villa’s dominant display.
At the City Ground, two-time European champions Forest booked their first continental semi-final since the 1983-84 Uefa Cup.
Porto defender Jan Bednarek was dismissed in the eighth minute for an ugly foul that caught Chris Wood on the knee and forced the New Zealand striker to limp off injured. (AFP)
