At present, there are several therapeutic approaches for targeting telomerase in tumors. One in particular, currently undergoing clinical trials, is based on synthetic lipid-modified oligonucleotide antagonists aimed at inhibiting the ribonucleoprotein subunit of human telomerase. However, while enabling efficient uptake, the lipid modifications reduce the potency of the therapeutic oligonucleotides compared to nonmodified oligonucleotides. Moreover, lipid modification may increase oligonucleotide accumulation in the liver causing undesirable hepatotoxicity. Noncovalent complexation strategies for cell-penetrating peptide (CPP)-mediated delivery present an option to circumvent the need for potency-reducing modifications, while allowing for a highly efficient uptake, and could significantly improve the efficiency of telomerase-targeting cancer therapeutics. Delivery of a nonlipidated locked nucleic acid/2'-O-methyl mixmer significantly inhibits the telomerase activity in treated HeLa cells. The inhibitory effect was further improved through addition of a CPP. Furthermore, calculated IC50-values for the oligonucleotide delivered by CPPs into HeLa cells are more than 20 times lower than telomerase inhibitor Imetelstat, currently undergoing clinical trials. These results emphasize the potential of CPP-mediated delivery of future pharmaceuticals and provide means by which to enhance an already promising therapeutic strategy for cancer treatment.