This study presents a partial Life Cycle Assessment (LCA) of greenhouse gas (GHG) emissions and carbon balance for 36 bread winter wheat cultivars under the conditions of the Right-Bank Forest-Steppe of Ukraine during 2020–2024. The assessment followed ISO 14040/14044 standards and IPCC (2006, 2019) guidelines with cradle-to-farm gate system boundaries. Total GHG emissions amounted to 1,938.2 kg CO2-eq/ha, with mineral fertilizer production (41.8%) and field N2O emissions (34.2%) as dominant sources. The carbon footprint varied from 236 to 335 kg CO2-eq/t depending on cultivar yield, representing a 42% difference attributable solely to cultivar selection under identical technology. Five highly carbon-efficient cultivars (<250 kg CO2-eq/t) were identified: Lehenda Bilotserkivska (236), Okhtyrchanka (238), Pryvitna (244), Optyma Odeska (244), and MIP Valensiia (248). The gross carbon balance was positive for all cultivars (+19.3 to +28.2 t CO2-eq/ha). The sequestration break-even point ranged from 77% to >100% straw retention depending on yield. Cultivar selection combined with straw management can modify the net carbon balance by up to 14,206 kg CO2-eq/ha. To achieve carbon neutrality, high-yielding cultivars should be combined with ≥75% straw retention.