We performed $J$-band observations of the host galaxies of nine narrow-line Seyfert 1 galaxies (NLS1). Seven of these sources have been detected at 37 GHz and are likely to host relativistic jets. Host galaxy properties of the jetted NLS1 galaxies are not yet well known, and investigating them is essential to get more insight into their characteristics and the possibly heterogeneous nature of the NLS1 population. It also helps us to understand the overall evolution of NLS1 galaxies and how do they fit into the big picture of active galactic nuclei (AGN). We used the 2D photometric image decomposition algorithm GALFIT to model the morphologies of the hosts. We were able to reliably model five of the nine host galaxies, three of which have also been detected at 37 GHz. All five host galaxies are late-type, four of them host pseudobulges, and four are barred. A surprisingly large fraction, three out of five, show signs of interaction. These results support the idea that spiral galaxies with pseudobulges are able to launch and maintain powerful jets. High fraction of interacting sources may indicate that mergers and interaction could affect the level of nuclear activity in NLS1 galaxies. This could also explain the diversity seen in the NLS1 galaxy population as a consequence of galaxy evolution via mergers and interaction.