Smith is leading a team as head of Plimsoll Wales, and is already working on a pair of series that the company says broadcasters will announce in “due course”.
He joined Plimsoll in 2015 as a Bristol-based executive producer, though he has spent much of the past decade living and working further west in Wales.
His most recent role saw him overseeing specials and live events such as National Geographic’s Earth Live, which was the channel’s most-watched live event in a decade.
Before joining Plimsoll, he ran BBC Two wildlife series Springwatch and produced Amazon with Bruce Parry and Tribe.
“Cardiff is an obvious expansion of our commitment to out-of-London production, tapping into the creative talent base that has grown up there, including BAFTA award winner James Smith,” said Mansfield, the former Zodiak USA chief.
Recent Plimsoll commissions include ITV’s Teach My Pet to Do That and Channel 4 series Rescue Dogs to Super Dogs, which Animal Planet is adapting for the US. It also received a 50-hour output order from Smithsonian Earth and Blue Ant International-backed natural history SVOD service Love Nature.