The byelection was triggered by the sudden resignation, for "personal reasons", of Northland MP Mike Sabin.
In the March 28 poll he will go up against NZ First leader Winston Peters, who announced his intention late last week, Labour's Willow-Jean Prime, Mana's Rueben Taipari Porter and Act's Robin Grieve. The Green Party is not contesting the byelection.
Mr Osborne immediately took leave from his job as Far North District Council asset manager until the election result is known.
He has previously managed Kaitaia's Te Ahu Centre and co-owns Doubtless Beauty with his wife Jodi. They live in Taipa and have two children.
He pledged to work to maintain a strong voice for Northland in John Key's government.
- more to come in Monday's Advocate.