Yes, children of any age — including infants — can perform حج, and their حج 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 نبی کریم Muhammad (صلی اللہ علیہ وسلم) and asked, 'Is there حج for this one?' He replied, 'Yes, and you will have a reward.' However, it is important to understand that a child's حج, while valid and rewarding, does not fulfill the واجب حج 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 حج again as their fard (واجب) حج.
For children who have reached the age of discernment (mumayyiz, generally around seven years old) and can understand the rituals, they enter احرام themselves with their guardian's permission and perform the rites as an adult would — طواف, سعی, standing at عرفات, and so on — with guidance and assistance from their parent or guardian. If they are unable to complete certain rites (such as stoning the جمرات 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 احرام on the child's behalf, carries them during طواف and سعی, and ensures they are present at عرفات and the other stations. The child's احرام garments follow the same rules as adults for boys; girls wear their normal modest clothing.
Practically speaking, taking children on حج requires careful planning. The physical demands of حج — long walks in extreme heat, massive crowds, sleep deprivation during the مزدلفہ night, and the multi-day stay in منیٰ 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.