This study examines the evolution of Shiite contract law from strict formalism to a consent-based approach, analyzing three key doctrinal shifts: (1) the relaxation of mandatory verbal formulas (sigha), (2) reinterpretation of past-tense phrasing (māḍawiyya), and (3) flexibility in offer-acceptance correspondence. Early jurists like al-Ṭūsī and al-Jawāhirī insisted on rigid formalities, viewing sigha as essential for validity and rejecting non-verbal transactions (muʿāṭāt). However, later scholars, including al-Anṣārī and contemporary jurists such as Khomeini and Makārim Shīrāzī, prioritized mutual intent (qasd), validating muʿāṭāt through customary practice (bināʾ al-ʿuqalā). The requirement of past-tense verbs was similarly reframed—while initially seen as necessary to convey definitive intent, jurists later accepted any phrasing that clearly expressed consent. Likewise, classical demands for exact mirroring and sequence between offer (ījāb) and acceptance (qabūl) were softened, with conditional acceptances treated as counter-offers, akin to modern principles in the CISG. A pivotal driver of this transition was jurists’ engagement with societal changes, notably the rise of written contracts, which gained legal recognition as literacy spread. The paper concludes that Shiite jurisprudence adapts formalities instrumentally, prioritizing evidentiary reliability over rigid structures, and anticipates further evolution with digital contracting. Ultimately, the shift reflects a broader move from textual formalism to substantive justice, anchored in the doctrine of bināʾ al-ʿuqalāʾ.