The Assyrian Church of the East affirms the full divinity and personhood of the Holy Spirit as the Third Person of the Trinity. The Spirit proceeds from the Father as one of the two primordial divine processions, coequal and coeternal with the Son. The church does not affirm the Filioque addition to the Creed (the Spirit proceeding from both Father and Son), maintaining instead the Eastern position of the Spirit's procession from the Father.

The Holy Spirit is understood to be intimately involved in the ongoing life of the Church. The epiclesis—the invocation of the Holy Spirit over the Eucharistic bread and wine in the Divine Liturgy—is a crucial moment in the Anaphora of Addai and Mari, calling down the Spirit to sanctify the gifts and unite the people to Christ. The Spirit is given in Baptism and Chrismation (anointing with oil), and the gifts and graces of the Spirit are understood to be active throughout the life of the believing community, though the church's tradition is not charismatic in the Pentecostal sense.