AbstractIn this research the weak decay ofBc+decays to theK+K−π+final state, which is being observed by LHCb collaboration for the first time, is calculated in the quasi-two-body decays which takes theBs0, χc0andD0resonances and weak annihilation nonresonant contributions into account. In this process, theBc+meson decays first intoBs0π+, χc0π+andD0π+intermediate states, and then theBs0, χc0andD0resonances decay intoK+K−components, which undergo final state interaction. The mode of theBc+ → D0(→K−π+)K+is also associated with the calculation, in this mode the intermediate resonanceD0decays to theK−π+final mesons. The resonancesBs0, χc0andD0effects in theBc+ → Bs0(→K+K−)π+,Bc+ → χc0(→K+K−)π+andBc+ → D0(→K+K−)π+,D0(→K−π+)K+decays are described in terms of the quasi-two-body modes. There is a weak annihilation nonresonant contribution in whichBc+decays to theK+K−π+directly, so the point-like 3-body matrix element$$ \left\langle {K}^{+}{K}^{-}{\pi}^{+}\left|u\overline{d}\right|0\right\rangle $$K+K−π+ud¯0is also considered. The decay mode of the$$ {B}_c^{+}\to {\overline{K}}^{\ast 0}(892){K}^{+} $$Bc+→K¯∗0892K+is contributed to the annihilation contribution. The branching ratios of quasi-two-body decays expand in the range of (2.12 ± 0.61) × 10−6to (7.56 ± 1.71) × 10−6.