Ms Mayer met the TV presenter and environmentalist, and other campaigners, to rally support for legislation to stop the import into Britain of body parts from big game animals killed abroad.
Body parts of elephants, bears, lions, hippos and zebras are among those currently allowed to be brought back from hunting trips.
Up to 25,000 animal parts have been brought into the UK as hunting trophies since the 80s, according to the Convention on International Trade in Endangered Species.
These figures include about 5,000 endangered species, such as black rhinos and polar bears.
Dunstable and Leighton Buzzard constituency’s MP hailed the Government’s pledge to implement a full ban on trophy hunting and is calling for legislation to be tabled soon so “we can consign to history this cruel blood sport once and for all.”
Ms Mayer, who has written to the Environment Secretary, said: “Trophy hunting is cruel, and immoral, and it is opposed by the public - they really do not want these magnificent, often endangered, animals to be slaughtered to decorate people's houses.
“I welcome the Government’s pledge to implement a full ban on imports of hunting trophies – this is really positive. I want legislation to be introduced so we can deliver on that pledge as soon as possible so we can consign to history this cruel blood sport once and for all.”
Mr Packham urged people to write to MP Alex Mayer, who has long advocated for a ban, to back legislation for all trophy hunting imports to become illegal.
A trophy-hunting ban is backed by nine in ten people, according to the Ban Trophy Hunting group.