Check the kiwi for blemishes. Bruises and holes can spread during the ripening process, causing the fruit to rot.
Place the kiwifruit in a paper or vented plastic bag. If you have another piece of ripening fruit, such as a banana or apple, put that in the bag as well. The ripening fruit emits ethylene gas, which speeds up the process.
Place the bag somewhere that's room temperature and free from direct sunlight and moisture. Check the kiwi the following day for ripeness. It may take two days to completely ripen.