The firm, which has offices in Preston, Blackburn, Blackpool and Chorley, acts for a number of agricultural clients as an official panel law firm of the National Farmers Union.
Partner in the rural team Geoff Tomlinson will lead the office alongside new recruits Alex Sykes and Catherine Courtney.
Solicitor Sykes has joined Napthens from a rural practice in north Cumbria. Before which he worked as a professional forest manager while Courtney will provide admin support.
Head of rural at Napthens Andrew Holden will divide his time between Penrith and his base in Lancashire.
He said: "We have been able to look after our clients well from our existing offices but as our rural service has grown we felt that a move to Cumbria with a permanent facility in Penrith would be a great boost.
"The appointment of Alex and Catherine means we have a significant rural team as we move to cement our place as a leading law firm in this specialised sector.
"We see the office in Penrith as a base to service our clients throughout Cumbria."