The MPs also alleged that Batuk has never carried out the legally required environmental and social impact assessments for its field exercises, and raised concerns over the possible use of white phosphorus, which they described as "notorious for the severity of the injuries it causes".
Residents reported respiratory issues, miscarriages, and livestock deaths due to toxic fumes and leftover military waste.
In one case, a ranger reportedly died after taking home unexploded ordnance from a Batuk range, while a child is said to have lost both arms and an eye after encountering another.
In its defence, Batuk said that independent environmental audits showed high levels of compliance with Kenyan regulations.
The investigating panel said Batuk had "persistently" declined to appear before the committee and instead "invoked claims of diplomatic immunity".
The British defence ministry said it had responded to the issues highlighted during the inquiry and "outlined the actions taken to address the concerns raised".
In a statement, the UK High Commission said it was prepared to investigate "where new allegations have come to light in the committee's report".
"We deeply regret the challenges which have arisen in relation to our defence presence in Kenya," it said.
But the parliamentary panel found the existing defence cooperation agreement between Kenya and the UK was "structurally flawed", saying the legal instrument has huge gaps.
It noted that "the offence of murder, despite its gravity, is not explicitly listed… as an offence deemed outside the course of official duty".
This, it argued, created a "significant obstacle to justice," adding that the existing oversight mechanism was largely ineffective.
The committee recommended the military agreement be amended to introduce a visiting forces code of conduct, zero-tolerance rules for gender-based violence, environmental obligations, and civilian oversight.
It also called on the Kenyan defence ministry to negotiate with the UK government on mechanisms to hold Batuk soldiers accountable for child support.