The first mention of Marwell occurs in a Saxon charter, granting lands, including those around the zoo, to the new monastery in Winchester (this was what later became known as Hyde Abbey). Sometime in the 1100s Henry de Blois, bishop of Winchester established a College of Secular Priests at Lower Marwell. A moated site containing various buildings within it, including a chapel where William of Wykeham 'held 60 ordinations in a day'. By 1306 the bishop of Winchester was Henry Woodlock, and it was he who granted, in 1310, a 'licence to enclose' to one Walter Woodlock (presumably a relative, though we don't know what the relationship between them was). Marwell Hall was built around four years later.
The estate was acquired by Corpus Christi College, Oxford in the early 1500s and its revenues used towards the upkeep of that college. A series of tenants, sub-tenants and so on occupied the hall over the next 300 years. Around 1530 Sir Henry Seymour acquired the Marwell Hall estate. He and his descendants (Sir John and Sir Edward Seymour) occupied the hall until 1638. Sir Henry Seymour was one of Jane Seymour's brothers, and it is believed that Henry VIII may have visited the hall on more than one occasion.
The hall then passed to Sir Henry Mildmay and his family occupying it for some years. During the English Civil War there was a minor skirmish involving 60 of Waller's men, who were billeted at the hall, and some 200 Royalists (who had spent much of the day drinking in Winchester). The Roundheads won, even though they were outnumbered by more than three to one.
Corpus Christi College eventually sold the whole estate in about 1882, and it was purchased by Rowland Standish. His family owned the hall until 1933 when the last of that branch of the family was killed in a car accident. In 1941 parts of the grounds of the hall were used as a temporary airfield by the Cunliffe-Owen Aircraft Company ' the managing director, a Mr Rex Hoyes, living in the hall. The company moved all the parts of its operations that required flying from their factory in Swaythling out to Marwell which was well outside the barrage over Southampton and made flying operations easier. This temporary, or 'dispersal' airfield as they were known, was in use until sometime in 1944. In the late 1960s the hall and its grounds were purchased by Mr John Knowles who created Marwell Zoological Park which opened its gates to the public in 1972.