To facilitate rapid replication and assembly of progeny, baculovirus is known to manipulate the host nuclear microenvironment by inducing chromatin changes in localization and architecture. However, the molecular mechanisms underlying these changes remain unknown. Here, we revealed that the nuclear lamina (NL) protein Lamin A/C interacts with the heterochromatin protein 1 alpha (HP1a) and identified the middle region of HP1a as critical for this interaction. Suppression of Lamin A/C and HP1a expression resulted in a significant inhibition of chromatin marginalization mediated by baculovirus infection. Moreover, the heterochromatin modification H3K9me3, which is recognized and bound by HP1a, also participated in the process of chromatin marginalization. Our live-cell imaging and quantitative analysis unveiled a passive function of marginal chromatin, which involves the formation of a physical barrier that impedes the nuclear egress of the nucleocapsids. Furthermore, baculovirus-induced nuclear F-actin altered the steady-state of intranuclear actin pool, thus regulating the nucleosome disassembly. Overall, our findings illustrate the molecular mechanisms dictating chromatin marginalization and structural alterations during baculovirus infection, shedding new light on the potential function of marginalized chromatin in the origin of its biphasic life cycle.