The former world number one was taken to two tie-breaks by the eighth seed before eventually overcoming his opponent 7-6 (2) 7-6 (7) in just over two hours in Beijing.
World number 13 Berrettini, who is nine years Murray's junior, reached the US Open semi-finals this year and put up a good fight against the Scot on Tuesday before falling just short in both sets.
Murray fought back after falling a break down in each set to record his second and biggest ATP Tour singles victory since he underwent hip surgery in January.
The 32-year-old broke Berrettini, who was serving for the first set, and went on to dominate the tie-break and again – in the second set – with Berrettini 2-0 up, the Scot hit back to level the scores before celebrating victory after a second tie-break.
On Thursday, Murray was knocked out of the Zhuhai Championships at the last-16 stage after a three-set tussle with Australia's Alex De Minaur as he continued his comeback after seeing off Tennys Sandgren in the opening round.
Last month, Murray committed to playing for four weeks in a row as this week's tournament in Beijing is sandwiched in between his outings in Zhuhai and his wild card appointment at the Rolex Shanghai Masters before he returns to Europe to compete in the European Open in Antwerp.
Next up for Murray is Wednesday's last-16 clash with compatriot Norrie, whose first-round opponent Cristian Garin took a nasty tumble during a first-set tie-break on Monday and – after losing it – retired injured.