Magnetic Janus colloids whose permanent dipole moments are radially shifted from the particle center exhibit broken interaction symmetry that alters self-assembly in fully three-dimensional suspensions. Using Brownian dynamics simulations of dilute, field-free systems, we examine how the radial dipolar shift $s$ and the dipolar coupling strength $\lambda$ affect nucleation, growth kinetics, orientational ordering, and cluster morphology. Across the simulated parameter range, aggregation follows a two-stage nucleation-growth scenario: an initial delayed nucleation stage is followed by sustained growth, after which the weighted mean cluster size obeys a long-time power law, $\langle N_c\rangle \sim t^z$, where the exponent $z$ depends on both $s$ and $\lambda$. For small shifts, head-to-tail alignment dominates, producing extended chainlike and looped aggregates. Increasing $s$ frustrates collinear bonding, broadens the bonded-pair orientational distribution, and promotes closure, branching, and compactification. At the largest simulated shifts, the cluster-size distribution shifts toward small, compact aggregates with partially compensated dipole orientations, and the growth exponent decreases systematically, indicating hindered coarsening. Comparison with previously reported quasi-two-dimensional aggregation shows that $s$ and $\lambda$ remain the governing control parameters, while fully three-dimensional motion enables out-of-plane rearrangements, higher local coordination, and three-dimensional cluster-closure pathways. These results show that, within the simulated dilute and field-free regime, radial dipole displacement provides a geometric control parameter for tuning aggregation pathways and morphology selection in three-dimensional magnetic Janus suspensions.

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• Self-assembly
• Colloids
• Janus particles
• Magnetic colloids
• Brownian dynamics