Yes, children of any age — including infants — can perform হজ্জ, and their হজ্জ is valid according to all four schools of Islamic jurisprudence. This is based on the authentic hadith in which a woman lifted up her child to নবী করীম Muhammad (সাল্লাল্লাহু আলাইহি ওয়া সাল্লাম) and asked, 'Is there হজ্জ for this one?' He replied, 'Yes, and you will have a reward.' However, it is important to understand that a child's হজ্জ, while valid and rewarding, does not fulfill the ওয়াজিব হজ্জ that becomes binding upon reaching puberty. Once the child reaches the age of puberty and meets the other conditions of obligation (financial and physical ability), they must perform হজ্জ again as their fard (ওয়াজিব) হজ্জ.
For children who have reached the age of discernment (mumayyiz, generally around seven years old) and can understand the rituals, they enter ইহরাম themselves with their guardian's permission and perform the rites as an adult would — তাওয়াফ, সাঈ, standing at আরাফাত, and so on — with guidance and assistance from their parent or guardian. If they are unable to complete certain rites (such as stoning the জামারাত due to the dangerous crowds), their guardian may perform those acts on their behalf. For children below the age of discernment (infants and toddlers), the parent or guardian makes the intention for ইহরাম on the child's behalf, carries them during তাওয়াফ and সাঈ, and ensures they are present at আরাফাত and the other stations. The child's ইহরাম garments follow the same rules as adults for boys; girls wear their normal modest clothing.
Practically speaking, taking children on হজ্জ requires careful planning. The physical demands of হজ্জ — long walks in extreme heat, massive crowds, sleep deprivation during the মুযদালিফা night, and the multi-day stay in মিনা tents — are challenging even for healthy adults. Parents should honestly assess whether bringing young children is feasible given the specific conditions. Consider the child's age, temperament, health, and your ability to care for them while completing your own rites. Many scholars advise that while taking children is rewarding, it should not come at the expense of the parents' ability to focus on their own worship and complete their rites properly. A stroller suitable for rough terrain is essential for toddlers, and extra supplies (diapers, formula, snacks, medications) should be packed generously.