Answer
It is commonly thought that the longest verse in the Bible is Esther 8:9, which says this:
“The king’s scribes were summoned at that time, in the third month, which is the month of Sivan, on the twenty-third day. And an edict was written, according to all that Mordecai commanded concerning the Jews, to the satraps and the governors and the officials of the provinces from India to Ethiopia, 127 provinces, to each province in its own script and to each people in its own language, and also to the Jews in their script and their language” (ESV).
Normally, this amount of content (80 words in the ESV translation) would have been broken up into two, three, or even four separate verses. But, for whatever reason, when the Bible was divided into verses, it was decided to leave all the content together, making Esther 8:9 the longest verse in the Bible.
Ranking other long verses provides different results, depending on the translation. Staying with the ESV, The second longest verse in the Bible is Revelation 20:4, which has 75 words. Third place is a tie between Joshua 8:33 and Ezekiel 48:21, both coming in at 74 words. Jeremiah 21:7 and Jeremiah 44:12 are tied for fourth with 73 words apiece. The fifth longest verse in the Bible is 2 Chronicles 2:14 with 68 words, and sixth is Ezekiel 46:9 (65 words).
Using the KJV, Esther 8:9 is still in first place with 90 words. The other verses listed above fall into this ranking:
Second longest verse: Jeremiah 21:7
Third longest verse: Ezekiel 46:9
Fourth longest verse (four-way tie): Joshua 8:33; 2 Chronicles 2:14; Ezekiel 48:21; and Jeremiah 44:12
Fifth longest verse: Revelation 20:4
However, if you count by the number of Hebrew/Greek words, Esther 8:9 is not the longest verse in the Bible. In the original languages, Revelation 20:4 has 58 words while Esther 8:9 has 43 words. So, the longest verse in the Bible in the original languages is Revelation 20:4, while the longest verse in the Bible in English translations is Esther 8:9.