The coordination of the relationship between new-type urbanization (NTU) and carbon emission reduction has become China's primary strategic goal. However, previous studies on this topic mainly examined the unidirectional impact of NTU on carbon emissions, while disregarding their potential relationship. This study establishes an evaluation system for measuring NTU and explores the bidirectional impact between NTU and total carbon emissions (TCE), per capita carbon emissions (PCE), and carbon emission intensity (CEI). The Yangtze River Economic Belt of China is selected as the study area, and the period from 2005 to 2019 is studied. The results show that: (1) The NTU levels in the upstream, midstream, and downstream regions of the Yangtze River increase from 0.148, 0.208, and 0.365 in 2005 to 0.465, 0.503, and 0.675 in 2019, suggesting that NTU levels tend to be balanced in these three reaches. (2) A positive bidirectional impact is found between NTU and TCE, as well as PCE in midstream and upstream regions, whereas in downstream regions, only a positive unidirectional effect of NTU on TCE and PCE is found. (3) Specifically, TCE plays the most significant role in promoting NTU in upstream regions, while NTU exerts the greatest pulling force on TCE and PCE in midstream regions. (4) Unlike the positive impact between NTU and TCE or PCE, there is a significant two-way inhibitory effect between NTU and CEI. (5) A three-step carbon emission reduction law is found in the process of NTU, where NTU towards low carbon development will experience NTU inhibits CEI, PCE, and TCE in sequential order. These findings provide an important reference for promoting a harmonious relationship between NTU and carbon emission reduction, helping governments formulate reasonable measures to achieve high-quality urban development and carbon emission reduction goals.