A former Labour councillor and special advisor to the Welsh government has been appointed as the new Future Generations Commissioner.
The Welsh Tories said Sophie Howe was a "Labour insider", while Friends of the Earth Cymru said there was a "real danger" the role could be compromised.
Meanwhile Diane McCrea has been named chairwoman of Natural Resources Wales.
Natural Resources Minister Carl Sargeant said they were "strong people" in "vital roles".
"The [Well-being of Future Generations] Act is about improving the social, economic, environmental and cultural well-being of Wales and having strong people in these important positions will help us achieve the Wales we want to see," he said.
Ms Howe, currently deputy police and crime commissioner for south Wales, was appointed to the £95,000-a-year post for a seven-year term following the recommendation of a cross-party panel.
She said she was "delighted and honoured", adding: "Wales is one of the first countries in the world to put sustainable development at the heart of everything it does."
Ms Howe will take up the newly-created post in February, and will stand down from her police role.
She had worked for Mr Sargeant as a special advisor while he was local government minister.
A spokesman for the Welsh Conservatives described Ms Howe as a "Labour insider", while party leader Andrew RT Davies said her "very strong identity link" to Labour was "a cause for concern".
He said commissioners should be more clearly appointed by the assembly rather than the first minister, but suggested ministers should get on with their jobs "instead of hiving a lot of these functions off".
"We are creating commissioners for this, commissioners for that," he said.
"What we want to do is see real improvement and real change here in Wales."
Plaid Cymru AM Simon Thomas called the appointment "strange" and suggested it "will raise eyebrows" in the sector.
"It doesn't appear that she has the qualifications or an interest in this field," he said.
"She does have experience in public bodies but not within sustainable development."
Friends of the Earth Cymru said: "This appointment clarifies the problem with the commissioner being accountable to the Welsh government, rather than the National Assembly for Wales.
"There's a real danger that the commissioner's role will be compromised because of a desire to please the government," a spokesman added, pointing to plans for an M4 relief road as an example.
Welsh Liberal Democrat leader Kirsty Williams called it a "bit rich" for opposition parties to criticise Ms Howe's appointment as a cross-party panel was behind the decision.
"My understanding is that she was the unanimous choice of the cross-party panel that decided her appointment, so it seems strange that Andrew RT Davies objected to her appointment," she said.
However, Plaid Cymru denied the choice was unanimous.
The members of the panel were Llyr Gruffydd for Plaid Cymru, Conservative Janet Haworth, William Powell for the Liberal Democrats and Joyce Watson for Labour.
Forty people applied for the job.
It is understood that the panel recommended Ms Howe be appointed from a shortlist, which was accepted by the first minister.
Ms McCrea, named as the new chairwoman of Natural Resources Wales (NRW), has held similar roles at housing charity Shelter Cymru and the Consumer Council for Water.
Analysis by Iolo ap Dafydd, BBC Wales environment correspondent
Announcing the new Future Generations Commissioner at the same time as the new NRW chairwoman and board members may have attracted more criticism than the Welsh government and its civil servants intended.
The lack of environment expertise was quickly pointed out by those within the conservation sector and that background leans more towards the social and economic benefits of the recently established Future Generations Act.
The £95,000 per annum salary of Sophie Howe as a former Labour councillor, special advisor and deputy police commissioner in south Wales was pointed out immediately.
But a "jobs for the boys" gibe is countered partly as members of all political parties in the assembly took part in recommending her.
Diane McCrea is another new face in the Welsh environment world as successor to Peter Matthews to chair the board of NRW.
Like him, her background is in water, but with direct experience of developing and delivering strategies and policies with customers and communities.