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Observational records are more often than not influenced by residual non‐climatic factors which must be detected and adjusted for prior to their usage. In this work, we present a novel approach, named Radiosounding HARMonization (RHARM), providing a homogenized data set of temperature, humidity and wind profiles along with an estimation of the measurement uncertainties for 697 radiosounding stations globally. The RHARM method has been used to adjust twice daily (0000 and 1200 UTC) radiosonde data holdings at 16 pressure levels in the range 1,000–10 hPa, from 1978 to present, provided by the Integrated Global Radiosonde Archive. Relative humidity (RH) data are limited to 250 hPa. The applied adjustments are interpolated to all reported levels. RHARM is the first data set to provide homogenized time series with an estimation of the observational uncertainty at each sounding pressure level. By construction, RHARM adjusted fields are not affected by cross‐contamination of biases across stations and are fully independent of reanalysis data. Analysis of trends for temperature, RH and winds highlights increased geographical coherency of trends over 1978–2000 globally, but especially in the Northern Hemisphere and South America. RHARM shows warming trends of 0.39 K/decade at 300 hPa in the Northern Hemisphere and of 0.25 K/decade in the tropics. The RHARM adjustments also reduce differences with the European Centre for Medium‐Range Weather Forecast ERA5 reanalysis, with the strongest effect in the Northern Hemisphere for temperature and relative humidity. For wind speed, the comparison indicates a good agreement with ERA5 in the troposphere. Plain Language Summary: Systematic observations of atmospheric parameters by balloon soundings have been collected regularly across the globe since decades. However, changes in the instrumentation, calculation algorithms, station re‐locations and other factors can influence the measurement time series, making the identification of climate signals difficult. The availability of measurement metadata, cross‐comparison with (sparser) reference networks and the application of statistical methods allows to greatly improve the physical consistency of the records. We developed the Radiosounding HARMonization (RHARM) methodology to provide users with homogenized radiosonde profiles of temperature, humidity, and wind, along with measurement uncertainties, for 697 locations globally and twice daily based on the Integrated Global Radiosonde Archive. Key features of RHARM are the provision of multiple fundamental atmospheric parameters, adjusted for spurious biases and the inclusion of measurement uncertainties estimated following the standards of the metrological community when available metadata permits. The current version of the RHARM data set can be used to investigate tropospheric weather and climate for the last four decades. Key Points: The Radiosounding HARMonization (RHARM) data set provides homogenized time series of temperature, relative humidity and wind profiles for hundreds of radiosonde stationsMetrologically accurate estimates of the observational uncertainty are provided together with each observation and variableFor all variables, RHARM increases the geographical coherency of estimated trends and the agreement with a modern atmospheric reanalysis [ABSTRACT FROM AUTHOR]