The unattenuated TeV $\gamma$-ray spectrum observed in some blazars is inconsistent with the $\gamma\gamma$ absorption by seed photons in the relativistic jet or the extragalactic background light (EBL) during extragalactic propagation. In addition, the efficiency of inverse-Compton emission is suppressed at such high energies. Ultrahigh-energy cosmic rays (UHECRs; $E\gtrsim10^{17}$ eV) accelerated in blazar jets can escape from their sources and interact with the cosmic background photons. The resultant $\mathrm{e^\pm}$ and $\gamma$-rays can induce electromagnetic cascade resulting in a photon spectrum peaking at $\sim1$ TeV energies. We propose that the line-of-sight component can be observed as coming from their respective sources. We consider a random turbulent extragalactic magnetic field to constrain the survival fraction of UHECRs along the observer's line of sight. A one-zone leptonic model is used to fit the synchrotron spectrum of the blazars. The higher-energy peak is explained by a combination of synchrotron self-Compton spectrum produced by the same relativistic electrons and the $\gamma$-rays from line-of-sight UHECR interactions. Overall, the lepto-hadronic model better explains the multiwavelength spectral energy distribution (SED). We also calculate the line-of-sight neutrino flux from these blazars corresponding to the luminosity required in $\gamma$-rays. We discuss the prospects of UHECR detection from these resolved sources.