Linear diblock copolymers are known to self-assemble into well-defined, phase-separated microstructures whose morphology is governed by the relative volume fractions of the constituent blocks. By utilizing this behavior, previous studies have created materials with nanoscale features for potential applications in lithography, photonic crystals, and surface coatings. The same self-assembly behavior is observed in bottlebrush block copolymers (BBCPs), although it remains less studied. Investigating the self-assembly of BBCPs and the effect of crosslinking on their microstructures may provide access to microstructures with larger tunable domain spacings. This work investigated the effect of block order and crosslinking on the microstructures of BBCPs by synthesizing triblock BBCPs with and without diazirine crosslinking units. These were compared with equivalent crosslinkable diblock BBCPs from a previous study. The triblocks were synthesized via a grafting-through approach using ring-opening metathesis polymerization (ROMP) to create the triblock from pre-synthesized macromonomers. The macromonomers were synthesized from norbornene-based initiators using either dodecyl acrylate or 4-methylcaprolactone to yield PDDA and P4MCL side chains. PDDA side chains were either end-functionalized with diazirine groups to enable crosslinking or left unfunctionalized. Two triblock BBCPs, with and without diazirine, with a PDDA volume fraction of fPDDA = 0.5 were synthesized by ROMP and then annealed to aid self-assembly. The diazirine-containing sample was then crosslinked and both were characterized using variable-temperature small-angle X-ray scattering (VT-SAXS) to determine their microstructure and domain spacing. The triblocks displayed a lamellar microstructure with a domain spacing of about 160 Å. This is a 40% reduction in domain spacing compared to an equivalent diblock, showing that block order clearly affects domain spacing. Furthermore, increasing the temperature from 30 °C to 190 °C resulted in a decrease in domain spacing. In the crosslinked sample, the decrease in domain spacing under higher temperature was reduced by a factor of 4, indicating thermal stabilization of the microstructure by crosslinking.