The article defines the preconditions for the efficient assessing the economic effectiveness of public-private partnerships in terms of investment and innovation activities (the need to identify the existing limitations of such assessment, which can help in achieving social, economic, informational, legal and other types of effects; the need to identify the genuine value added of a public-private partnership entity creation/improvement (it is about the utility for public and private partners and other stakeholders); the need to implement in the public-private partnership projects those options that will maximize the expected effects, taking into account regulatory constraints and the minimum cost of resources involved; the need to compare the expected and actual effects of the public-private partnership project). The risks of public-private partnership projects are identified and characterized, including those identified by the current regulatory framework (level of product demand, investment costs, operating expenses, operating income, financing conditions and discount rates, taxes and contributions, as well as currency courses and price dynamics). Methodological provisions on quantification of public-private partnership risks are presented. The main methods and approaches to assessing the cost-effectiveness of public-private partnership in terms of investment and innovation activities were displayed (classical financial methods, qualitative analysis tools, probabilistic methods, portfolio analysis, project approach, budgetary approach, qualitative, financial or combined models). Traditional financial techniques in the field of such economic efficiency estimation are considered (profitability index, payback period, internal and average rate of return, level of investments profitability, etc.). Listed are the so-called new practical guidelines aimed at assessing the cost-effectiveness of public-private partnerships in terms of investment and innovation activity, in particular: Total Cost of Ownership (TCO), C/SCSC (Cost/Schedule Control Systems Criteria – cost-time diagnosis), IT Scorecard (Modified Balanced Scorecard Application (taking into account known public-private partnerships projections of a balanced scorecard), Activity Based Costing (ABС - applying functional and value analysis), Applied Information Economics (AIE), Total Economic Impact (TEI), Total Value of Opportunities (TVO), Rapid Economic Justification (REJ). It is summarized that theory and practice have formed many methods and approaches to evaluate the economic efficiency of public-private partnership in the conditions of investment and innovation activity development. Each of them has its advantages and disadvantages, as well as clearly defined conditions of practical application. Two or more of these approaches should be used to make more substantive conclusions on the cost-effectiveness assessment.