Apparently you are supposed to start novenas for the Feast of the Immaculate Conception on November 29 and have them end on the vigil of feast, which would be December 7. But I always start the novena on November 30 and have it end on the actual feast day, December 8.

So without further ado, here it is!

Immaculate Virgin! Mary, conceived without sin! Remember, thou wert miraculously preserved from even the shadow of sin, because thou wert destined to become not only the Mother of God, but also the mother, the refuge, and the advocate of man; penetrated therefore, with the most lively confidence in thy never-failing intercession, we most humbly implore thee to look with favor upon the intentions of this novena, and to obtain for us the graces and the favors we request. Thou knowest, O Mary, how often our hearts are the sanctuaries of God, Who abhors iniquity. Obtain for us, then, than angelic purity which was thy favorite virtue, that purity of heart which will attach us to God alone, and that purity of intention which will consecrate every thought, word, and action to His greater glory. Obtain also for us a constant spirit of prayer and self-denial, that we many recover by penance that innocence which we have lost by sin, and at length attain safety to that blessed abode of the saints, where nothing defiled can enter.

O Mary, conceived without sin, pray for us who have recourse to thee.

V. Thou are all fair, O Mary.
R. Thou art all fair, O Mary.
V. And the original stain is not in thee.
R. And the original stain is not in thee.
V. Thou art the glory of Jerusalem.
R. Thou art the joy of Israel
V. Thou art the honor of our people.
R. Thou art the advocate of sinners.
V. O Mary.
R. O Mary.
V. Virgin, most prudent.
R. Mother, most tender.
V. Pray for us.
R. Intercede for us with Jesus our Lord.
V. In thy conception, Holy Virgin, thou wast immaculate.
R. Pray for us to the Father Whose Son thou didst bring forth.
V. O Lady! aid my prayer.
R. And let my cry come unto thee.

Let us pray

Holy Mary, Queen of Heaven, Mother of Our Lord Jesus Christ, and mistress of the world, who forsakest no one, and despisest no one, look upon me, O Lady! with an eye of pity, and entreat for me of thy beloved Son the forgiveness of all my sins; that, as I now celebrate, with devout affection, thy holy and immaculate conception, so, hereafter I may receive the prize of eternal blessedness, by the grace of Him whom thou, in virginity, didst bring forth, Jesus Christ Our Lord: Who, with the Father and the Holy Ghost, liveth and reigneth, in perfect Trinity, God, world without end. Amen.