The film was praised by some members of the LGBT community for its portrayal of the gay character, but people from anti-LGBT groups commented negatively on Mammootty's social media pages criticising the actor for his role and asking for a boycott of the film. Muslim clerics and Christian priests also criticized the film's representation of homosexuality, suggesting that it would "brainwash the youth".
Critical response Kathal - The Core received mostly positive reviews from critics. Janani K. of
India Today gave 4 out of 5 stars and wrote, "
Kaathal - The Core is not just about the coming out, it's also about how these characters move on in life after the divorce. The last shot is dedicated to all the LGBTQIA+ members." Sajin Shrijith of
Cinema Express gave 4 out of 5 stars and wrote, "
Kaathal is arguably the most daring attempt from Malayalam cinema so far, mainly owing to one of its biggest superstars spearheading a film that asks some much-needed questions about a complex topic that doesn't have to be so." Anna Mathews of
The Times of India gave 3.5 out of 5 stars and wrote, "Good movies can make society think and even initiate change.
Kaathal - The Core might be one such." Sukanya Shaji of
The News Minute gave 3.5 out of 5 stars and wrote, "The heart of
Kaathal - The Core is, undoubtedly, the relationship between Mammootty's Mathew Devassy and Jyothika's Omana, and the heartbreaking dignity with which they help each other out of their predicaments." Manoj Kumar R. of
OTTPlay gave 4 out of 5 stars and wrote, "
Kaathal – The Core navigates through a myriad of sensitive subjects and personal choices deeply influenced by the age-old societal concern of "What will people say?"." S. R. Praveen of
The Hindu wrote, "
Kaathal beautifully uses a conventional family drama setting to tackle a subject that is still largely a taboo in the industry and the larger society; it is quite a triumph in that sense." Princy Alexander of
Onmanorama wrote, "Just like Nivin Pauly and Geethu Mohandas's
Moothon,
Kaathal The Core will be remembered for its unconventional theme and for lending Mammootty one more praise-worthy character in his illustrious career." Sarath Ramesh Kuniyl of
The Week gave 4.5 out of 5 stars and wrote, "
Kaathal – The Core is a watershed moment in Malayalam cinema, much like
The Great Indian Kitchen. Both Baby and Mammootty have shattered a glass ceiling, the sound of which, one hopes, will reverberate loudly in the society and for long." Nikhil Sebastian of
Pinkvilla gave 4 out of 5 stars and wrote, "
Kaathal stands as another masterpiece from Jeo Baby and Mammootty. With a compelling plot and a poignant subject, the movie succeeds in establishing a strong emotional connection with the audience throughout its two-hour runtime." Harshini S. V. of
Film Companion wrote, "
Kaathal – The Core speaks about the struggles of coming out and addresses the need for acceptance in a conventional society. And if that's not bold and progressive, I am not sure what is." Priyanka Sundar of
Firstpost gave 4 out of 5 stars and wrote, "Joe Baby, the director who also gave us the
Great Indian Kitchen masterfully depicts the life of Omana and Mathew so sensibly and with a sensitive approach. It is rare to see a film so well made when it centers on a relationship — especially one that is forced to stick with heteronormativity." Analysing the movie, Sajesh Mohan of
Onmanorama wrote "In
Kaathal - The Core, Jeo Baby's writers Adarsh Sukumaran and Paulson Skaria occasionally resort to the FAQ format to elucidate the necessity of proper understanding and acceptance of sexual orientation. However, it's not these preaching sessions that drive the point home; it's the characters." Sujatha Narayanan of
The Quint wrote "Kaathal – The Core is a sensitive, dignified, and nuanced film that brings to fore the importance of how big stars like Mammootty and Jyotika (who returned to the big screen after three years) fit into humble places with much grace. With Kaathal, Mammootty also squashes pre written stereotypes for how a hero should be on screen, what kind of roles a megastar can take up, and whether an actor with a good market should do an experimental, bold film at all. Kaathal makes us all want to be better human beings – and that's the most important achievement of Jeo Baby's film."
Box office Kathal - The Core recorded an opening of ₹1.05 crore. The film recorded a 19% jump in revenue on its second day in theatres by earing ₹1.25 crore. On its first weekend, the film grossed ₹1.6 crores on Saturday with a 42.04% occupancy rate and grossed ₹1.75 crores on Sunday.
Kathal - The Core grossed a total of Rs 5 crore within four days of its release. The film reportedly collected ₹16.25 lakhs from Aries Plex Theatre,
Thiruvananthapuram. By its first weekend the film grossed ₹1 crore from ROI circuits. The next day, the film grossed around 6.25 crore. By its 8th day it grossed around ₹7.95 crores. == Awards and honours ==