The Millennium Window is located above the 1662 Font, opposite the south door to the church. It was commissioned from local artist Jane Grey to commemorate the millennium. It was installed in 2004 after a public appeal.
The main roundel shows Oswald's Tree surrounded by an 'O' for Oswald. On the tree are emblems connected with the life of Christ. Clockwise: the nativity star, the moon, the Lamb of God, the Bible, the pelican, regarded as a symbol of piety, the year of our Lord 2000, grapes and corn, mentioned in the gospels, the Greek monogram for Christ with a fish, a pomegranate representing the Resurrection, and a dove for the Holy Spirit.
The tracery lights above the roundel are the emblems of various bodies and societies in the town: left to right from the top: Cambrian Railways, Round Table, Royal British Legion, Shropshire County Council, Oswestry Town Council, Rotary International, Lions International, Women's Royal Voluntary Service, Orthopaedic Hospital, Royal Artillery, Oswestry Borough Council, Oswald's Cross of Prayer and silver dish, Oswald's crown and the sword which slew him, Lichfield Diocese, Masons and Oswestry School.