Yes, when a Catholic has committed a serious or mortal sin, sacramental confession is the ordinary way to reconcile the sinner with Christ and His Church.
Confession is, for the Catholic, the sacramental way of obtaining pardon for sin and of submitting his offenses to the mercy and forgiving grace of God.
In this sacrament Jesus forgives our sins, no matter how terrible they are, as long as we repent and are sorry for them and are resolved, even though we are weak, not to commit the sins again. We trust in the help of God’s grace to do so.
Repentance is a change of heart in which the sinner, helped by God’s grace, turns back to his Father in Heaven and accepts His loving forgiveness. Our Lord never refuses His merciful love to the person of humble and contrite heart. God continues to speak to man even though he keeps on refusing Him.
Our Christian life on earth is a spiritual warfare. Therefore we are subject to temptations and sins. But our Lord Jesus has given us, through His Church, the Sacrament of Penance, the sacrament of forgiveness, so that we may obtain pardon and peace from God and be reconciled with the Church.
The sign of the Sacrament of Penance consists of the sinner’s act of repentance by word or gesture, his confession of sins, his willingness to make reparation (penance), and the priest’s words of absolution, “I absolve you in the name of the Father and of the Son and of the Holy Spirit.”