The officer was spotted rounding up the geese by campaigner Ian Carroll. When questioned he said they were being relocated due to large numbers at parks in West Bromwich and Tipton.
Mr Carroll, who has led a campaign to stop the culling of geese in Sandwell, was even sent photos of geese by another officer and told they were being released.
However, it was later revealed that the birds were killed.
It has dragged Sandwell Council into a storm for which it has been forced to apologise.
The authority has been criticised by the Local Government Ombudsman (LGO), which launched an investigation following a complaint and ruled that it 'misled' Mr Carroll about the culling of the geese and that he was made to go to 'extra trouble to get to the truth'.
The council has apologised and was told by the LGO to pay the complainant £150. Bosses said the officer's actions breached its code of conduct.
Mr Carroll said he would not accept the £150 compensation as he did not wish to 'gain personally'.
The culling of Canada geese at Dartmouth Park and Victoria Park proved to be hugely controversial. A campaign launched calling for the measure to be stopped was backed by thousands of people.
A total of 220 Canada geese were culled in 2014 and 2015 at the two parks, as the authority claimed numbers had become 'out of control'. The LGO said the council did not break any laws in culling the birds.
The LGO investigation centred around an allegation that a council worker referred to as Officer Y had in 2013 and again in 2014 told Mr Carroll, named in the LGO's report as Mr B, in Victoria Park that the geese had been relocated and not culled.
The campaigner had noticed a drop in numbers of the birds and was keen to find out what had happened to them.
Following the publication of the report, Mr Carroll, 41, from West Bromwich, told the Express & Star: "It was only through a Freedom of Information request and the LGO that I found out the truth. If it were not for that it would probably have been swept under the carpet. It was only through sheer luck that I happened to be there and see what they were doing."
The LGO report, which referred to Mr Carroll as Mr B, said: "Mr B was at that park in 2013 and saw a council contractor rounding up the geese. Officer Y and the contractors told Mr B that the council had relocated the geese. Mr B knew that relocation is illegal and so he questioned the council about this.
Another officer sent him some photographs of geese telling him these were the geese being released."
It said that in 2014, Mr Carroll noticed a large number of the geese had gone. Officer Y again told him that it had relocated the geese. Mr Carroll challenged the council about this and it later admitted that Officer Y had misled Mr B and the council had in fact culled the geese in 2013 and 2014, using a licensed contractor.
The report continued: "The council has accepted that it misled Mr B about culling geese at a local park. It should apologise to him and pay £150 in recognition of the extra trouble he was put to trying to find out the truth."
Council bosses took the decision to cull some geese as numbers in the borough's parks had grown to more than 1,000.
There were concerns about the amount of faeces in parks, which was said to contain harmful bacteria if swallowed.
Previously, parks workers had pricked eggs to try and control numbers but chiefs said the practice was not having enough of an effect.
Earlier this year, council bosses agreed to end the culling of geese under the weight of pressure from the public.
Mr Carroll said: "They need to introduce some kind of policy to make sure this never happens again."
Sandwell Council's chief executive Jan Britton said: "We sincerely apologise to the complainant for being misled but we welcome the ombudsman's findings that our actions were lawful."