Polanski said there were two policing provisions, Operation Ford and Operation Bridger, which provided security and safety support for councillors and MPs, respectively.
"I am in the unusual situation as a London Assembly member and leader of a party where I haven't fallen under either," he added.
"The Home Office since the local elections have reviewed that and now I fall under Operation Ford. I welcome the movement on that and that's provided me with some extra safety and some extra steps."
It is also understood the Green Party does pay for some private security for its leader.
He has previously spoken about "heightened intrusion and safety risk" as well as "antisemitic and homophobic abuse" since becoming leader - with two arrests being carried out by police.
A Home Office spokesperson said: "No politician should be facing the threat of violence, abuse, or harassment – they must be able to go about their vital work safely and freely.
"The government keeps security provisions for elected representatives under regular review."
Representatives are encouraged "to liaise with their local police force if they have concerns about their safety", the spokesperson said.
The Green Party have been contacted for comment.
Polanski's remarks come amid a growing chorus of voices over whether politicians are being provided with enough security.
On Tuesday Andy Burnham said a serious review of MPs' security was needed after politics had "darkened" over the past decade.
"It's easy to blame social media, but it feels like it's having some impact in just building that kind of toxicity that's around the political debate," he said.
It followed a row between Reform UK and the government about the level of security provided to its leader Nigel Farage.
Reform UK's Treasury spokesman Robert Jenrick had made accusations of a "dereliction of duty".
He claimed Farage had not been given the security he needed, after it emerged Reform turned down a government-funded security offer last year.
The Home Office said Jenrick's comments were "categorically untrue" and that ministers were not responsible for deciding MPs' security.
Politicians' safety had already become a big concern after the murders of Conservative MP Sir David Amess in 2021 and Labour MP Jo Cox in 2016.
In May 2024 the Conservative government announced a £31m package to increase security.
The two police initiatives mentioned by Polanski are national drives to "strengthen the safety and security" of people in prominent roles.
Former head of counter-terrorism policing Neil Basu warned on Tuesday a high level of protection to all 650 MPs would need "thousands" of new police officers to be recruited.
Widdecombe was found dead in her home last Thursday after police believe she was attacked there a day earlier.
A white British man, 28, arrested on Saturday in South Yorkshire, is being held on suspicion of murder and on suspicion of commission, preparation or instigation of acts of terrorism.
