The former Rangers captain will join Killie on a three-year deal to team up with boss Gary Locke at Rugby Park.
McCulloch, 37, was deemed surplus to requirements at Ibrox after Rangers' new management team of Mark Warburton and David Weir arrived in June.
The former Wigan Athletic midfielder won three top-flight league titles and two Scottish Cups with Rangers.
McCulloch, who played many of his 46 games for Rangers last season in central defence, joins striker Kris Boyd and full-back Stevie Smith in making the move to Kilmarnock from Ibrox this summer.
Scotland international McCulloch was involved with Locke in Kilmarnock's preparations for Saturday's friendly against Berwick Rangers.
He joined Wigan from Motherwell in March 2001 and, after more than six years there, moved to Rangers for £2.25m.

A dog walker spotted the body in Vernatt's Drain, near the Pinchbeck Road bridge in Spalding, on Sunday.
Police recovered the body from the water after being alerted shortly after 14:00 GMT.
Officers had been initially treating the death as unexplained, but said they were now classing it as not suspicious.
The man's details are yet to be released.

A referendum on the UK's membership of the EU is to be held later this year.
The survey indicates that only 11% of of the chamber's members in Northern Ireland support a British exit (Brexit).
That compares to 30% of those surveyed in the rest of the UK.
The Chamber of Commerce has about 1,200 members in Northern Ireland.
About 250 of those responded to the poll.
More than half of the respondents (60%) said that Prime Minister David Cameron's renegotiated EU deal is unlikely to change how they will vote.
The results come on the eve of crunch Brussels talks, which are expected to result in a deal.
Eighty-four per cent of those surveyed in Northern Ireland  also say that there has been no impact on their sales and orders as of yet, due to the uncertainty of Britain's future within the EU.
Commenting on the results, President of Northern Ireland Chamber of Commerce Stephen McCully said the findings suggest that "the renegotiation is having little impact on day-to-day business - or the vote of the business community".
He said that this was because many made up their minds before knowing the outcome of negotiations, effectively discounting them as irrelevant.
"For businesspeople, this is a question of in or out," he said.
"Those within Northern Ireland who are firmly wedded to the EU have said that Brexit will leave us stranded outside the EU, and coping with the re-emergence of a land border with the Republic of Ireland.
"Emotion has a part in all decision making and it will do so here, but there is a duty to ensure decisions are as well informed as they can be."
Clarification: An earlier version of this article omitted the number of respondents to the Chamber of Commerce survey.

Konta beat world number 60 Kristyna Pliskova of the Czech Republic 6-4 6-7 (11-13) 6-3.
Her next opponent will be another Czech, Katerina Siniakova, who beat Serbian Nina Stojanovic 6-3 6-4.
Siniakova caused a surprise in the second round by defeating second seed Simona Halep.
Konta looked in control early on against her opponent - the twin sister of world number six Karolina Pliskova - as she took the first set with a single break of serve.
Neither player could force a break point in the second set and in the resulting tie-break Konta wasted two match points before the big-serving Pliskova levelled the match on her fifth set point.
But Konta stayed firm in the final set, claiming the break and reaching the semi-final on her fifth match point.
"I am very happy to have extended my stay here," she said.
"She is one of the best servers on tour so I knew I was going to have a hard time on her service games. I was very happy I was able to get that break in the third and see it out in the end."
Lee McCulloch will sign for Kilmarnock in a player-coach role, his representative has confirmed.
[NEXT_CONCEPT]
The death of a man found in a Lincolnshire waterway is not being treated as suspicious, police have said.
[NEXT_CONCEPT]
A survey of Chamber of Commerce members in Northern Ireland suggests that 81% will vote for the UK to remain in the European Union (EU).
[NEXT_CONCEPT]
British number one Johanna Konta continued her good start to 2017 by reaching the semi-finals of the Shenzhen Open in China.