Navalny was arrested soon after he touched down in Sheremetyevo – the plane was diverted away from Moscow.
Foreign Affairs Minister Nanaia Mahuta said that New Zealand is "concerned at the detention of Alexei Navalny and calls for his immediate release".
"Civil society and political opposition must be able to operate freely – these are essential elements of democratic societies," she said in a statement.
Mahuta is one of many political leaders to condemn Navalny's arrest.
Outgoing US secretary of state Mike Pompeo said the detention was the latest in a series of attempts to silence Navalny and other opposition figures who are critical of Russian authorities.
"Confident political leaders do not fear competing voices, nor commit violence against or wrongfully detain political opponents."
UK Prime Minister Boris Johnson said it was "outrageous" that a chemical weapon was used against Navalny.
"The Russian Government must now explain what happened to Mr Navalny – we will work with international partners to ensure justice is done."
German Chancellor Angela Merkel said the arrest was "arbitrary" and her Foreign Minister, Steffen Seibert, called on Putin to release Navalny at once.
Navalny has been an outspoken critic of long-time President Putin and has investigated corruption in his inner circle.
According to the Guardian, the official cause of the arrest was failure to appear at a parole hearing – he has been detained for 30 days.
He could face years behind bars if a suspended sentence he received in 2014 is amended to a prison term.
The Guardian also reported that Navalny was in good spirits on the plane shortly before his arrest, telling journalists who flew with him from Berlin: "I am not afraid."
He said he was "extremely happy" to be returning to Russia after almost five months recuperating in Germany.
