The Multi-sensor dataset of environmental conditions in smart office consists of time series data acquired from sensors deployed in smart office rooms located in ICAR-CNR, for environmental monitoring. Various sensors located in about 25 rooms were used for recording data including temperature and humidity. Raw sensor data samples were collected continuously at a frequency of 1 Hz over a period from 1 of June 2023 to 30 June 2023. The dataset can be useful in the analysis of different tasks, including data-driven algorithms for analyzing the comfort of people. In particular, the research community might be interested in investigating information extraction and decision making applied to smart offices. Furthermore, by applying artificial intelligence (AI) algorithms on such data collected over long periods, it is possible to extract, e.g., patterns that reveal environmental changes in the office living conditions.