The approval at the Upper House loosens post-World War II constraints on use of force by the military to its own self-defence only.
The legislation, passed by the more powerful lower house in July, sparked debate about whether the nation should shift away from its pacifist ways to face growing security challenges.
Since Thursday, Opposition parties had been pulling out all the stops to delay the vote.
They introduced a series of no-confidence measures against government ministers and parliamentary leaders, made filibuster speeches and one even made slow “cow walk” to a ballot box to cast his vote. The maneouvers were destined to fail, but ate up hours of time requiring debate and votes on each measure.
The law will allow the military to defend Japan’s allies even when the country isn’t under attack, work more closely with the U.S. and others.
They will also be able participate more fully in international peacekeeping.