Previous studies have found that gifted children experience symptoms such as existential anguish, anxiety, depression, experiential avoidance, and cognitive fusion. The inherent intensity and sensitivity of these young people may make them more susceptible to significant emotional distress and existential concerns. Endeavoring to address such issues, we designed a second-generation mindfulness-based intervention, called the “Atencion plena para altas capacidades” (APAC; Mindfulness for Giftedness). This paper presents the pretreatment, posttreatment, and 12-month follow-up findings on the implementation of the program in a sample of 22 gifted children in Spain. The program comprised eight weekly 90-min group sessions covering mindfulness, emotional intelligence, emotional regulation, acceptance, values, compassion, and self-compassion. The program’s efficacy was measured using standardized, validated tools (the Child and Adolescent Mindfulness Measure, the Avoidance and Fusion Questionnaire for Youth, the Children’s Depression Inventory, the State Trait Anxiety Inventory for Children, the Positive and Negative Affect Schedule for Children, and the Emotional Skills and Competence Questionnaire) at pretreatment, posttreatment, and 12-month follow-up time periods.. Our study’s findings at the posttreatment stage suggested that the APAC program improved the emotional abilities and reduced negative symptoms. Results from the 12-month follow-up assessment stage appeared to uphold these findings. However, we recommend that future second-generation mindfulness-based interventions for gifted children should include more activities and exercises that address the meaning of life and other related existential worries of particular concern to these young people.