Oil-impregnated self-lubricating polymers are widely used in the field of aviation and aerospace, petrochemical industry and mechanical engineering due to their excellent self-lubrication, maintenance-free and environmental stability. Traditionally, they are fabricated by the two-step method, i.e. fabrication of porous structure followed by filling the lubricant in the pores, which is not only specific equipment requirement and time-consuming, but results poor lubricating and mechanical performance due to the uneven distribution of lubricant and the high porosity. Herein, the oil-impregnated polymer with superior self-lubricating and mechanical performances is achieved with a novel one-pot strategy by pre-embedding the oil-impregnated cotton fibres in the polymer matrix. With the pre-embedding of the oil-impregnated cotton fibre, the oil-impregnated cotton fibres/polymer composites (OCFP) with the oil content rate up to 42.86% were achieved in one step. Moreover, the oil impregnated in OCFP was found nearly no leak. The resultant OCFP thus exhibited the average friction coefficient reduced by 98.63% and the compression strength improved by 367.74%. The oil-impregnated polymers with excellent self-lubricating and mechanical performance fabricated by the facile one-pot fabricating strategy are promising to be widely used in the engineering fields.