Code-switching in Facebook posts is seen as a problem in the Philippine educational setting as it contributed to the deterioration of English language skills among Filipino students. This qualitative research employing textual analysis aimed to examine the phenomenon of code-switching embedded in the 51 instances of Facebook posts and comments of Filipino Facebook users. The types, functions, and formations of code-switching in Facebook posts were identified and coded. The reasons of the participants for code-switching in their Facebook posts were similarly explored. Results revealed that function words, content words, and linguistic play were most common. It further revealed that the social functions of code-switching were identified as referential, directive, expressive, phatic and poetic were apparent types of insertional switches. Furthermore, the results showed that formation of code-switching in the Facebook posts were intersentential, intra-sentential, tag and intra-word. Moreover, the reasons behind code-switching in the posts were to identify about a particular topic, to provide emphasis about a message, to express group identity, to clarify speech content, to meet real lexical need, to exclude others, to indicate and express emotions, and to keep up with the linguistic trend.