Aptamers with target-specific binding properties have emerged as an alternative to antibodies. Nucleic acid aptamers are short single-stranded oligonucleotides that can fold into unique three-dimensional structures. Nucleic acid aptamers are selected from random libraries in vitro by using the SELEX (Systematic Evolution of Ligands by Exponential Enrichment) technology. Likewise, peptide aptamers are short peptides that can be selected in vitro by using different strategies including phage display, ribosome display, or mRNA display. Aptamers are superior to antibodies with regard to ease of production, high stability, small size, and low cost. Therefore, aptamers find broad use in different biotechnological and therapeutic applications. Among them, aptamer use in virus detection and antiviral therapy is one of the attractive applications. The present Covid-19 pandemic and life-threatening viral infections reveal the need for rapid therapeutic solutions that can efficiently target viral mechanisms. In this respect, the chapter is mainly focused on aptamers with antiviral activity, as well as the use of aptamers in viral detection platforms. First, we summarize aptamer selection technologies that can be performed in vitro. Among them, we briefly explain ribosome display, mRNA display and SELEX (Systematic Evolution of Ligands by Exponential Enrichment) technologies. Then, we review aptamers targeting viral proteins and viral invasion mechanisms. In addition, we give an overview of aptamers developed against viruses. We also discuss the major hurdles in aptamer use, as well as the strategies to improve the drug potential of aptamers.