Using the Panel Data Approach (PDA) of Hsiao et al. Journal of Applied Econometrics, 7(5), 705-740 (2012) in combination with the LASSO method, this article aims to measure the effect of the Brexit process on the United Kingdom’s real economy up to 2019Q2. The results are twofold: Firstly, compared to the existing literature, the PDA improves the measurement of the impact of Brexit on the real economy regarding computation intensity, the feasibility of statistical inference and a wider application area. Secondly, the estimated counterfactuals for the UK show that the Brexit process has played a crucial role in the UK’s economy, leading to lower GDP (growth rates), lower private consumption, lower gross fixed capital formation (GFCF) and higher exports. On average, GDP growth has declined between 1.3 and 1.4 percentage points, whereby the cumulative loss ranges between 48 and 54 billion British pounds. Moreover, private consumption in the UK has declined 4.7 billion British pounds quarterly on average. The predicted counterfactuals show that the impact of the Brexit process on GFCF has begun in 2018Q1, whereby the average treatment effect amounts to −2.9 billion British pounds. The UK’s exports increased since the referendum, most likely due to the depreciation of the British pound post-Brexit. The average quarterly effect of the Brexit process on exports is estimated here at 4.8 billion British pounds.