The comments came in a statement issued during Stoltenberg's trip to Japan following a visit to South Korea on which he urged Seoul to increase military support to Ukraine and gave similar warnings about rising tension with China.
"The world is at a historical inflection point in the most severe and complex security environment since the end of World War II," the two leaders said on Tuesday.
It also raised concerns about Russia's nuclear threats, joint military drills between Russia and China near Japan, and North Korea's development of nuclear weapons.
Stoltenberg told reporters a Russian victory in Ukraine would embolden China at a time when it is building up its military, "bullying its neighbours and threatening Taiwan".
He added: "This war is not just a European crisis, but the challenge to the world order.
"Beijing is watching closely, and learning lessons that may influence its future decisions. What is happening in Europe today could happen in East Asia tomorrow."
While NATO groups 30 countries in Europe and North America, Stoltenberg has said its members are affected by global threats.
Kishida and South Korean President Yoon Suk-yeol became the first leaders from their countries to attend a NATO summit last year, joining as observers.
China has previously criticised NATO's efforts to expand its alliances in Asia. Russia, which calls its invasion of Ukraine a "special operation", has repeatedly cast NATO's expansion as a threat to its security.
Late last year, Japan unveiled sweeping plans to beef up its defence capabilities, changes once unthinkable for a pacifist country that will make it the third-biggest military spender after the United States and China.
Bolstering its co-operation with NATO in areas from maritime security and arms control to cyberspace and disinformation will further help to respond to the changing strategic environment, the statement said.
