This article is dedicated to the study of multilingual approaches to sentiment analysis of texts in Finnish, Hungarian, and Bulgarian. For Finnish and Hungarian, which are characterized by complex morphology and agglutinative grammar, an analysis was conducted using both traditional rule-based methods and modern machine learning techniques. In the study, BERT, XLM-R, and mBERT models were used for sentiment analysis, demonstrating high accuracy in sentiment classification. The inclusion of Bulgarian was motivated by the opportunity to compare results across languages with varying degrees of morphological complexity, which allowed for a better understanding of how these models can adapt to different linguistic structures. Datasets such as the Hungarian Emotion Corpus, FinnSentiment, and SentiFi were used to evaluate model performance. The results showed that transformer-based models, particularly BERT, XLM-R, and mBERT, significantly outperformed traditional methods, achieving high accuracy in sentiment classification tasks for all the languages studied.