Matt Watson reviewed Knock Knock for Film Trance. He gave the film a 7.5/10 and said the following:
The set-up’s nothing new and the outcome’s a given, but its brutal intensity – compounded by the sheer bat-shit-craziness of Izzo and De Armas and the ever-growing desperation of a hysterical Reeves – makes Roth’s seductive examination of human sexuality a thoroughly uncomfortable, yet strangely engrossing watch.
Kat Smith reviewed the film for The Hollywood News and gave it 3/5 stars.
Vicki Shields reviewed the film for The Shields Gazette. Overall it was a negative review and she said the following:
It’s billed as a tense horror-thriller, but Knock Knock would sit more comfortably in the comedy section.
The latest film from Hostel creator Eli Roth is so bad it’s hilarious.
I don’t think I was the only one who found the film surprisingly funny.
This film is definitely good for a chuckle, but if you’re actually after a tense horror-thriller then I wouldn’t recommend it.