How do I use Boto3 to launch an EC2 instance with an IAM role?

Just an addition to the great answer by helloV (I can not comment due to reputation limitations). I encountered the same error message of "The parameter iamInstanceProfile.name may not be used in combination with iamInstanceProfile.arn. So only one key is allowed. I experimented with both and using

IamInstanceProfile={ 'Name': 'ExampleInstanceProfile' }

works for me, but not using

IamInstanceProfile={'Arn':'arn:aws:iam::123456789012:instanceprofile/ExampleInstanceProfile'}

I am using boto3 version 1.4.4

Note: Some Boto3 versions accept either Arn or Name but all versions accept Name. I suggest using the role name only.

IamInstanceProfile={
    'Arn': 'string',
    'Name': 'string'
}

If your profile name is ExampleInstanceProfile and the ARN is arn:aws:iam::123456789012:instance-profile/ExampleInstanceProfile

ec2.create_instances(ImageId='ami-1e299d7e',
                     InstanceType='t2.micro',
                     MinCount=1, MaxCount=1,
                     SecurityGroupIds=['Mysecuritygroup'],
                     KeyName='mykeyname',
                     IamInstanceProfile={
                            'Arn': 'arn:aws:iam::123456789012:instanceprofile/ExampleInstanceProfile'
                            'Name': 'ExampleInstanceProfile'
                     })