In this article, multiwalled carbon nanotubes (MWCNTs) with polymer shells based on cross-linked divinylbenzene (DVB) were controllably synthesized via direct in situ free-radical polymerization, thereby producing a hybrid composed of a core-shell microstructure and MWCNT center. The coated MWCNT hybrids (DVB@MWCNFs) were ultimately compounded with polystyrene (PS) to prepare nanodielectric composites with high dielectric constant and low dielectric loss. The composite containing 30 wt% DVB@MWCNTs showed a dielectric constant of 114 at 1 kHz, which is 42.2 times that of pure PS (2.7), and a low dielectric loss of 0.015. Modulation of these dielectric properties can be attributed to the good dispersion of DVB@MWCNTs in the PS matrix and the formation of an insulating DVB layer via DVB@MWCNTs. This insulating layer reduces the dielectric loss of the percolative composites, which is generally high because of insulator-conductor transitions near the percolation threshold. (C) 2016 Elsevier Ltd. All rights reserved.