While Halloween has largely become a secular holiday, it still commemorates the beginning of the Catholic feast of All Saints Day.
All solemnities in the Catholic Church begin on the evening before the feast day. All Saints Day is on November 1, and so the evening of October 31, Halloween, inaugurates the liturgical celebration.
Any Catholic can mark the beginning of this feast by reciting Evening Prayer, or Vespers, as it is often called.
All Saints Day has a special "Evening Prayer I" in the Liturgy of the Hours, which can be prayed with a physical copy of Christian Prayer, online through Universalis, or through various apps, such as iBreviary.
Praying Evening Prayer on Halloween is one way to recognize the liturgical feast of All Saints Day and sanctify the secular holiday that has become part of Western culture.
If you are short on time, here is the concluding prayer for Evening Prayer on Halloween.