Having played four first-class matches for Combined Services in 1956 and 1957, whilst doing his national service, Edrich made his first-class debut for Surrey in their final fixture of the 1958 season. The following year, he came to the fore, scoring 1,799 runs at an average of 52.91. Over the next four years he and Micky Stewart became a very effective opening partnership for the county, to the extent that both were called up for England for the Test series against the West Indies, who were dominating the sport at this time. Despite Edrich's strong performances for his county, he managed a total of only 108 Test runs in six innings facing bowlers including Hall, Sobers and Griffith.

However, an opportunity to break back into the international side arose when Geoffrey Boycott was injured during Australia's tour of England in 1964. Edrich was called up to the side for the Second Test, at Lord's, and did not disappoint, scoring 120. The match ended in a draw due to rain. However, he was not selected for the 1964–65 tour of South Africa.

Injuries to other players resulted in another recall to the England side for the Third Test against New Zealand at Headingley in July 1965, where he scored 310 not out. This innings spanned over eight hours, and included 52 fours and five sixes – 238 runs or 77% of his innings. Commentators at the time said that he might have broken the existing Test record of 365 within another 90 minutes or so if his captain, Mike Smith, had not felt it necessary to declare the innings closed. However, a week later during the First Test against South Africa, he suffered a blow to the head from a short-pitched delivery by Peter Pollock. This was before helmets came into use, and he was forced to retire hurt on 7 not out.Wisden named Edrich as Cricketer of the Year in 1966 for his achievements in 1965, alongside Colin Bland, Dick Motz, Graeme Pollock and brother Peter Pollock. As well as his Test triple century, he had scored a total of 2,319 runs at an average of 62.67 during the season, including eight hundreds. At one stage, in nine successive innings he scored 139, 121*, 205*, 55, 96, 188, 92, 105 and 310*. Not previously known as a big hitter, he struck forty-nine sixes during the course of the season.

He had by now become an established member of the England batting line-up, rarely omitted unless injured. Beginning with the 1965–66 Ashes series, he sometimes batted at number three rather than, as hitherto, opening the innings. In the 1970–71 Ashes series his 687 runs (52.85) kept him at the crease