What is the context?
This verse gives the positive direction at the center of Matthew 6:25–34. Jesus has named the worries of food, drink, and clothing, pointed to God's care in creation, and reminded His hearers that their Father knows their needs. Seeking His kingdom comes within that invitation to trust.
The verb is ζητέω, zēteō (zay-TEH-oh). Thayer's Greek Lexicon explains its use here as aiming at or striving after something. The instruction concerns what directs the life. God's reign and righteousness are to take first place.
All these things refers back to the food, drink, and clothing already discussed. Earlier in the chapter Jesus warned against storing up earthly treasure and trying to serve both God and money. The promise is about the Father's care within a life directed toward Him.
The next verse acknowledges the trouble each day brings. Giving God's kingdom first place provides a direction for facing life, while the Father's knowledge gives a reason for trust.
How is this passage commonly understood?
Christians commonly understand this verse as calling for God's reign and righteousness to guide life ahead of anxious pursuit of material security. Wesley's note on Matthew 6:33 describes God reigning in the heart and filling the life with righteousness, while the Catholic Catechism, 305, places the words within a child's trust in the Father's care.
Where does this fit in God's plan?
God's kingdom changes life from within. When discussing disputes about food, Romans 14:17–19 describes its priorities as righteousness, peace, and joy in the Holy Spirit, then calls believers to pursue peace and build one another up. Seeking His reign has visible consequences in how His people treat each other.
The Father also delights to give His people the kingdom. Luke 12:29–34 connects seeking it with that assurance and with generosity toward the poor. God's care and gift become reasons for an openhanded life, whose hope reaches beyond possessions.
What is our position?
Our study Prayer and Faith reads this verse as a call to seek God and His will, rather than demanding outcomes from Him. It understands provision as following the Father's care, not as something owed because a request was worded correctly. Our companion study What Does Prayer Look Like? develops the same emphasis on surrender and trust while recognizing that asking is not itself sinful.