We propose a paper that provides education on commonly used long-acting injectable antipsychotics (LAIs) to improve primary care based mental health interventions in patients with severe mental illnesses (SMIs) such as schizophrenia, schizoaffective disorder, and bipolar disorders. With the expanding interface of primary care and psychiatry across all healthcare settings, it has become increasingly important for primary care clinicians to have a broader understanding of common psychiatric treatments, including LAIs. Long-acting injectable antipsychotics have been shown to be helpful in significantly improving treatment adherence, preventing disease progression, improving treatment response, decreasing readmission rates, and reducing social impairment. We discuss evidence-based indications and guidelines for use of long-acting injectable antipsychotics. We provide an overview of the treatment of SMI with LAIs, mainly focusing on the most commonly used long-acting injectable antipsychotics, advantages and disadvantages of each, along with outlining important clinical pearls for ease of practical application. Equipped with increased familiarity and understanding of these essential therapies, primary care clinicians can better facilitate early engagement with psychiatric care, promote more widespread use, and thus significantly improve the wellbeing and quality of life of patients with severe mental illness.