Guzal Darreh () is a city in, and the capital of, Bagh Helli District of Soltaniyeh County, Zanjan province, Iran. It also serves as the administrative center for Guzal Darreh Rural District.
At the time of the 2006 National Census, the population was 1,604 in 489 households, when it was the village of Guzal Darreh-ye Sofla in Guzal Darreh Rural District of the former Soltaniyeh District in Abhar County. The following census in 2011 counted 1,448 people in 484 households. The 2016 census measured the population of the village as 1,532 people in 542 households, by which time the district had been separated from the county in the establishment of Soltaniyeh County. The rural district was transferred to the new Bagh Helli District. Guzal Darreh-ye Sofla was the most populous village in its rural district.
The village was converted to a city as Guzal Darreh in 2024.