In metaphase of mitosis, chromosomes align at the equatorial plane of the spindle, which is crucial for correct completion of later phases. Chromosome alignment is regulated by forces exerted by dynamics of kinetochore fibers (k-fibers) and polar ejection forces. This study explored a role of motor protein kinesin-8, which is known as one of main regulators of kfiber dynamics, in chromosome alignment. Here, I showed that kinesin-8 regulates velocity and amplitude of kinetochore movements, while experiments of laser ablation of k-fibers after depletion of kinesin-8 indicate it has a role in limiting the growth of microtubules. Furthermore, chromosome alignment could be influenced by bridging fibers, new class of microtubules in the spindle that connect sister k-fibers and balance the tension on sister kinetochores. This possibility is investigated by developing and applying optogenetic approach to manipulate localization of PRC1 protein, which specifically crosslinks microtubules within the bridging fibers. Acute removal of PRC1 led to partial disassembly of bridging fibers and elongation of their antiparallel overlaps, which was accompanied by misaligned and lagging chromosomes. Kif4A/kinesin-4 and Kif18A/kinesin-8 were also found within bridging fibers and largely lost upon PRC1 removal, suggesting that these proteins regulate the overlap length of bridging microtubules. Finally, a model is proposed where PRC1-mediated crosslinking of bridging microtubules and recruitment of kinesins to the bridging fiber promote chromosome alignment by overlap length-dependent forces transmitted to the associated k-fibers.