The paper aims to present key preconditions for the development of organizational knowledge ecosystem inside an audit firm. The audit activities represent a specific context for knowledge management, especially what concerns knowledge sharing and generation of new knowledge in organizational environment of formal rules and standards. We present the survey of audit firm employees (68) and their management by discussing the key challenges related to the dynamic knowledge sharing and new knowledge creation inside an audit firm. The paper investigates the nature of knowledge within an audit firm and analyses the cultural and structural aspects of KM practices that may lead to the emergence of ecosystem for sharing the existing and generating new knowledge. The paper adopts the intra-organizational perspective to knowledge ecosystem. The audit firm operates as knowledge organization that, despite its strong formal side, is a complex dynamic system of knowledge professionals, who form the different communities of practice inside the firm. Research presented in this paper helped identify the key challenges and opportunities for the emergent knowledge partnerships inside the professional audit firm. The key cultural preconditions behind the effective knowledge ecosystem - trust-based relations, organizational culture, positive horizontal and vertical relations, and strong intrinsic motivation to share knowledge - are in place. Research findings also reveal a good fit between the employee expectations and organizational practices. However, certain challenges need to be addressed, such as bringing out and embodying the tacit knowledge of employees, and the need for continuous upgrading of the processes of knowledge creation and integration. To establish an effective and sustainable knowledge ecosystem inside the professional services firm, the paper argues for striking a delicate balance between the formal and informal parts of organization, as well as its KM system.