The readiness to change among drug addicts is a key strength for successful treatment. Self-awareness, self-determination, and self-efficacy have been identified as the fundamentals of readiness that should be embraced by drug addicts while in treatment. In this article, the shared data were applied to assess the effect of individual psycho-educational intervention based on integrated self-awareness and self-determination theories (i-SEAZ) on self-efficacy amongst opioid-dependent patients undergoing methadone treatment (MT). The effectiveness of the i-SEAZ module was evaluated in a total of 75 opioid-dependent MT participants from five Methadone Clinics under the Ministry of Health, Malaysia located across Klang Valley. The experimental group consisted of 38 participants who received 10 sessions of individual i-SEAZ alongside MT, whereas 37 participants of the control group only received MT. The shared data were collected through three questionnaires, namely Scale for Self-Consciousness Assessment (SSCA), Treatment Motivation Questionnaire (TMQ), and General Self Efficacy (GSE). Data collection was performed twice; the first instance was two weeks prior to initiation of i-SEAZ (pretest), and the second was two weeks post completion of i-SEAZ (posttest). The extracted data were precisely represented in terms of means and standard deviations (SDs).