[6][7] Critical reception for The Fowl Twins Deny All Charges was positive, meeting with praise from most reviewers.

Kirkus Reviews praised the book, writing: "Colfer [continuously] strings dazzling displays of high tech, heartwarming peeks at the family dynamics of the closely knit if decidedly eccentric Fowl clan, dolphin-back rides, huge blobs of slime (some of it explosive), and a climactic exhibition of prejudice gone off the rails that is intense enough to leave readers queasy.

"[8] The Irish Times praised the novel as an "offer [of a] page-turning adventure with a side of ridiculous fun", numbering it among the "best children’s books of the year".

[9] while Laughing Place praised how "Colfer has proven that you can capture lightning in a bottle twice with this supremely hilarious and joyful read", and of his "gift with language and for creating such likable characters that makes this reader chuckle from page to page.

"[10] Better Reading complimented the novel's "multi-faceted" characters and for "action sequences [that] are jam-packed [with a] dialled-up [form of] craziness [at] maximum levels in a kind of literary challenge.